Module:Citation/CS1

    From Nonbinary Wiki
    Revision as of 14:42, 12 December 2015 by m>Trappist the monk (is_parameter_ext_wikilink() fix;)

    Documentation for this module may be created at Module:Citation/CS1/doc

    
    local z = {
    	error_categories = {};		-- for categorizing citations that contain errors
    	error_ids = {};
    	message_tail = {};
    	maintenance_cats = {};		-- for categorizing citations that aren't erroneous per se, but could use a little work
    	properties_cats = {};		-- for categorizing citations based on certain properties, language of source for instance
    }
    
    --[[--------------------------< F O R W A R D   D E C L A R A T I O N S >--------------------------------------
    ]]
    local dates, year_date_check	-- functions in Module:Citation/CS1/Date_validation
    
    local cfg = {};					-- table of configuration tables that are defined in Module:Citation/CS1/Configuration
    local whitelist = {};			-- table of tables listing valid template parameter names; defined in Module:Citation/CS1/Whitelist
    
    --[[--------------------------< I S _ S E T >------------------------------------------------------------------
    
    Returns true if argument is set; false otherwise. Argument is 'set' when it exists (not nil) or when it is not an empty string.
    This function is global because it is called from both this module and from Date validation
    
    ]]
    function is_set( var )
    	return not (var == nil or var == '');
    end
    
    --[[--------------------------< F I R S T _ S E T >------------------------------------------------------------
    
    Locates and returns the first set value in a table of values where the order established in the table,
    left-to-right (or top-to-bottom), is the order in which the values are evaluated.  Returns nil if none are set.
    
    This version replaces the original 'for _, val in pairs do' and a similar version that used ipairs.  With the pairs
    version the order of evaluation could not be guaranteed.  With the ipairs version, a nil value would terminate
    the for-loop before it reached the actual end of the list.
    
    ]]
    
    local function first_set (list, count)
    	local i = 1;
    	while i <= count do															-- loop through all items in list
    		if is_set( list[i] ) then
    			return list[i];														-- return the first set list member
    		end
    		i = i + 1;																-- point to next
    	end
    end
    
    --[[--------------------------< I N _ A R R A Y >--------------------------------------------------------------
    
    Whether needle is in haystack
    
    ]]
    
    local function in_array( needle, haystack )
    	if needle == nil then
    		return false;
    	end
    	for n,v in ipairs( haystack ) do
    		if v == needle then
    			return n;
    		end
    	end
    	return false;
    end
    
    --[[--------------------------< S U B S T I T U T E >----------------------------------------------------------
    
    Populates numbered arguments in a message string using an argument table.
    
    ]]
    
    local function substitute( msg, args )
    	return args and mw.message.newRawMessage( msg, args ):plain() or msg;
    end
    
    --[[--------------------------< E R R O R _ C O M M E N T >----------------------------------------------------
    
    Wraps error messages with css markup according to the state of hidden.
    
    ]]
    local function error_comment( content, hidden )
    	return substitute( hidden and cfg.presentation['hidden-error'] or cfg.presentation['visible-error'], content );
    end
    
    --[[--------------------------< S E T _ E R R O R >--------------------------------------------------------------
    
    Sets an error condition and returns the appropriate error message.  The actual placement of the error message in the output is
    the responsibility of the calling function.
    
    ]]
    local function set_error( error_id, arguments, raw, prefix, suffix )
    	local error_state = cfg.error_conditions[ error_id ];
    	
    	prefix = prefix or "";
    	suffix = suffix or "";
    	
    	if error_state == nil then
    		error( cfg.messages['undefined_error'] );
    	elseif is_set( error_state.category ) then
    		table.insert( z.error_categories, error_state.category );
    	end
    	
    	local message = substitute( error_state.message, arguments );
    	
    	message = message .. " ([[" .. cfg.messages['help page link'] .. 
    		"#" .. error_state.anchor .. "|" ..
    		cfg.messages['help page label'] .. "]])";
    	
    	z.error_ids[ error_id ] = true;
    	if in_array( error_id, { 'bare_url_missing_title', 'trans_missing_title' } )
    			and z.error_ids['citation_missing_title'] then
    		return '', false;
    	end
    	
    	message = table.concat({ prefix, message, suffix });
    	
    	if raw == true then
    		return message, error_state.hidden;
    	end		
    		
    	return error_comment( message, error_state.hidden );
    end
    
    --[[--------------------------< A D D _ M A I N T _ C A T >------------------------------------------------------
    
    Adds a category to z.maintenance_cats using names from the configuration file with additional text if any.
    To prevent duplication, the added_maint_cats table lists the categories by key that have been added to z.maintenance_cats.
    
    ]]
    
    local added_maint_cats = {}														-- list of maintenance categories that have been added to z.maintenance_cats
    local function add_maint_cat (key, arguments)
    	if not added_maint_cats [key] then
    		added_maint_cats [key] = true;											-- note that we've added this category
    		table.insert( z.maintenance_cats, substitute (cfg.maint_cats [key], arguments));	-- make name then add to table
    	end
    end
    
    --[[--------------------------< A D D _ P R O P _ C A T >--------------------------------------------------------
    
    Adds a category to z.properties_cats using names from the configuration file with additional text if any.
    
    ]]
    
    local added_prop_cats = {}														-- list of property categories that have been added to z.properties_cats
    local function add_prop_cat (key, arguments)
    	if not added_prop_cats [key] then
    		added_prop_cats [key] = true;											-- note that we've added this category
    		table.insert( z.properties_cats, substitute (cfg.prop_cats [key], arguments));		-- make name then add to table
    	end
    end
    
    --[[--------------------------< A D D _ V A N C _ E R R O R >----------------------------------------------------
    
    Adds a single Vancouver system error message to the template's output regardless of how many error actually exist.
    To prevent duplication, added_vanc_errs is nil until an error message is emitted.
    
    ]]
    
    local added_vanc_errs;															-- flag so we only emit one Vancouver error / category
    local function add_vanc_error ()
    	if not added_vanc_errs then
    		added_vanc_errs = true;													-- note that we've added this category
    		table.insert( z.message_tail, { set_error( 'vancouver', {}, true ) } );
    	end
    end
    
    
    --[[--------------------------< I S _ S C H E M E >------------------------------------------------------------
    
    does this thing that purports to be a uri scheme seem to be a valid scheme?  The scheme is checked to see if it
    is in agreement with http://tools.ietf.org/html/std66#section-3.1 which says:
    	Scheme names consist of a sequence of characters beginning with a
       letter and followed by any combination of letters, digits, plus
       ("+"), period ("."), or hyphen ("-").
    
    returns true if it does, else false
    
    ]]
    
    local function is_scheme (scheme)
    	return scheme and scheme:match ('^%a[%a%d%+%.%-]*:');						-- true if scheme is set and matches the pattern
    end
    
    
    --[=[-------------------------< I S _ D O M A I N _ N A M E >--------------------------------------------------
    
    Does this thing that purports to be a domain name seem to be a valid domain name?
    
    Syntax defined here: http://tools.ietf.org/html/rfc1034#section-3.5
    BNF defined here: https://tools.ietf.org/html/rfc4234
    Single character names are generally reserved; see https://tools.ietf.org/html/draft-ietf-dnsind-iana-dns-01#page-15;
    	see also [[Single-letter second-level domain]]
    list of tlds: https://www.iana.org/domains/root/db
    
    rfc952 (modified by rfc 1123) requires the first and last character of a hostname to be a letter or a digit.  Between
    the first and last characters the name may use letters, digits, and the hyphen.
    
    Also allowed are IPv4 addresses. IPv6 not supported
    
    domain is expected to be stripped of any path so that the last character in the last character of the tld.  tld
    is two or more alpha characters.  Any preceding '//' (from splitting a url with a scheme) will be stripped
    here.  Perhaps not necessary but retained incase it is necessary for IPv4 dot decimal.
    
    There are several tests:
    	the first character of the whole domain name including subdomains must be a letter or a digit
    	single-letter/digit second-level domains in the .org TLD
    	q, x, and z SL domains in the .com TLD
    	i and q SL domains in the .net TLD
    	single-letter SL domains in the ccTLDs (where the ccTLD is two letters)
    	two-character SL domains in gTLDs (where the gTLD is two or more letters)
    	three-plus-character SL domains in gTLDs (where the gTLD is two or more letters)
    	IPv4 dot-decimal address format; TLD not allowed
    
    returns true if domain appears to be a proper name and tld or IPv4 address, else false
    
    ]=]
    
    local function is_domain_name (domain)
    	if not domain then
    		return false;															-- if not set, abandon
    	end
    	
    	domain = domain:gsub ('^//', '');											-- strip '//' from domain name if present; done here so we only have to do it once
    	
    	if not domain:match ('^[%a%d]') then										-- first character must be letter or digit
    		return false;
    	end
    	
    	if domain:match ('%f[%a%d][%a%d]%.org$') then								-- one character .org hostname
    		return true;
    	elseif domain:match ('%f[%a][qxz]%.com$') then								-- assigned one character .com hostname (x.com times out 2015-12-10)
    		return true;
    	elseif domain:match ('%f[%a][iq]%.net$') then								-- assigned one character .net hostname (q.net registered but not active 2015-12-10)
    		return true;
    	elseif domain:match ('%f[%a%d][%a%d]%.%a%a$') then							-- one character hostname and cctld (2 chars)
    		return true;
    	elseif domain:match ('%f[%a%d][%a%d][%a%d]%.%a%a+$') then					-- two character hostname and tld
    		return true;
    	elseif domain:match ('%f[%a%d][%a%d][%a%d%-]+[%a%d]%.%a%a+$') then			-- three or more character hostname.hostname or hostname.tld
    		return true;
    	elseif domain:match ('^%d%d?%d?%.%d%d?%d?%.%d%d?%d?%.%d%d?%d?') then		-- IPv4 address
    		return true;
    	else
    		return false;
    	end
    end
    
    
    --[[--------------------------< I S _ U R L >------------------------------------------------------------------
    
    returns true if the scheme and domain parts of a url appear to be a valid url; else false.
    
    This function is the last step in the validation process.  This function is separate because there are cases that
    are not covered by split_url(), for example is_parameter_ext_wikilink() which is looking for bracketted external
    wikilinks.
    
    ]]
    
    local function is_url (scheme, domain)
    	if is_set (scheme) then														-- if scheme is set check it and domain
    		return is_scheme (scheme) and is_domain_name (domain);
    	else
    		return is_domain_name (domain);											-- scheme not set when url is protocol relative
    	end
    end
    
    
    --[[--------------------------< S P L I T _ U R L >------------------------------------------------------------
    
    Split a url into a scheme, authority indicator, and domain.
    If protocol relative url, return nil scheme and domain else return nil for both scheme and domain.
    
    When not protocol relative, get scheme, authority indicator, and domain.  If there is an authority indicator (one
    or more '/' characters following the scheme's colon), make sure that there are only 2.
    
    ]]
    
    local function split_url (url_str)
    	local scheme, authority, domain;
    	
    	url_str = url_str:gsub ('(%a)/.*', '%1');									-- strip path information (the capture prevents false replacement of '//')
    
    	if url_str:match ('^//%S*') then											-- if there is what appears to be a protocol relative url
    		domain = url_str:match ('^//(%S*)')
    	elseif url_str:match ('%S-:/*%S+') then										-- if there is what appears to be a scheme, optional authority indicator, and domain name
    		scheme, authority, domain = url_str:match ('(%S-:)(/*)(%S+)');			-- extract the scheme, authority indicator, and domain portions
    		authority = authority:gsub ('//', '', 1);								-- replace place 1 pair of '/' with nothing;
    		if is_set(authority) then												-- if anything left (1 or 3+ '/' where authority should be) then
    			domain = nil;														-- set to nil which will cause an error message
    		end
    	end
    	
    	return scheme, domain;
    end
    
    
    --[[--------------------------< L I N K _ P A R A M _ O K >---------------------------------------------------
    
    checks the content of |title-link=, |series-link=, |author-link= etc for properly formatted content: no wikilinks, no urls
    
    Link parameters are to hold the title of a wikipedia article so none of the WP:TITLESPECIALCHARACTERS are allowed:
    	# < > [ ] | { } _
    except the underscore which is used as a space in wiki urls and # which is used for section links
    
    returns false when the value contains any of these characters.
    
    When there are no illegal characters, this function returns TRUE if value DOES NOT appear to be a valid url (the
    |<param>-link= parameter is ok); else false when value appears to be a valid url (the |<param>-link= parameter is NOT ok).
    
    ]]
    
    local function link_param_ok (value)
    	local scheme, domain;
    	if value:find ('[<>%[%]|{}]') then											-- if any prohibited characters
    		return false;
    	end
    
    	scheme, domain = split_url (value);											-- get scheme or nil and domain or nil from url; 
    	return not is_url (scheme, domain);											-- return true if value DOES NOT appear to be a valid url
    end
    
    
    --[[--------------------------< C H E C K _ U R L >------------------------------------------------------------
    
    Determines whether a URL string appears to be valid.
    
    First we test for space characters.  If any are found, return false.  Then split the url into scheme and domain
    portions, or for protocol relative (//example.com) urls, just the domain.  Use is_url() to validate the two
    portions of the url.  If both are valid, or for protocol relative if domain is valid, return true, else false.
    
    ]]
    
    local function check_url( url_str )
    	if nil == url_str:match ("^%S+$") then										-- if there are any spaces in |url=value it can't be a proper url
    		return false;
    	end
    	local scheme, domain;
    
    	scheme, domain = split_url (url_str);										-- get scheme or nil and domain or nil from url; 
    	return is_url (scheme, domain);												-- return true if value appears to be a valid url
    end
    
    
    --[=[-------------------------< I S _ P A R A M E T E R _ E X T _ W I K I L I N K >----------------------------
    
    Return true if a parameter value has a string that begins and ends with square brackets [ and ] and the first
    non-space characters following the opening bracket appear to be a url.  The test will also find external wikilinks
    that use protocol relative urls. Also finds bare urls.
    
    The frontier pattern prevents a match on interwiki links which are similar to scheme:path urls.  The tests that
    find bracketed urls are required because the parameters that call this test (currently |title=, |chapter=, |work=,
    and |publisher=) may have wikilinks and there are articles or redirects like '//Hus' so, while uncommon, |title=[[//Hus]]
    is possible as might be [[en://Hus]].
    
    ]=]
    
    local function is_parameter_ext_wikilink (value)
    local scheme, domain;
    
    	value = value:gsub ('([^%s/])/[%a%d].*', '%1');								-- strip path information (the capture prevents false replacement of '//')
    
    	if value:match ('%f[%[]%[%a%S*:%S+.*%]') then								-- if ext wikilink with scheme and domain: [xxxx://yyyyy.zzz]
    		scheme, domain = value:match ('%f[%[]%[(%a%S*:)(%S+).*%]')
    	elseif value:match ('%f[%[]%[//%S*%.%S+.*%]') then							-- if protocol relative ext wikilink: [//yyyyy.zzz]
    		domain = value:match ('%f[%[]%[//(%S*%.%S+).*%]');
    	elseif value:match ('%a%S*:%S+') then										-- if bare url with scheme; may have leading or trailing plain text
    		scheme, domain = value:match ('(%a%S*:)(%S+)');
    	elseif value:match ('//%S*%.%S+') then										-- if protocol relative bare url: //yyyyy.zzz; may have leading or trailing plain text
    		domain = value:match ('//(%S*%.%S+)');									-- what is left should be the domain
    	else
    		return false;															-- didn't find anything that is obviously a url
    	end
    
    	return is_url (scheme, domain);												-- return true if value appears to be a valid url
    end
    
    
    --[[-------------------------< C H E C K _ F O R _ U R L >-----------------------------------------------------
    
    loop through a list of parameters and their values.  Look at the value and if it has an external link, emit an error message.
    
    ]]
    
    local function check_for_url (parameter_list)
    local error_message = '';
    	for k, v in pairs (parameter_list) do										-- for each parameter in the list
    		if is_parameter_ext_wikilink (v) then									-- look at the value; if there is a url add an error message
    			if is_set(error_message) then										-- once we've added the first portion of the error message ...
    				error_message=error_message .. ", ";							-- ... add a comma space separator
    			end
    			error_message=error_message .. "&#124;" .. k .. "=";				-- add the failed parameter
    		end
    	end
    	if is_set (error_message) then												-- done looping, if there is an error message, display it
    		table.insert( z.message_tail, { set_error( 'param_has_ext_link', {error_message}, true ) } );
    	end
    end
    
    
    --[[--------------------------< S A F E _ F O R _ I T A L I C S >----------------------------------------------
    
    Protects a string that will be wrapped in wiki italic markup '' ... ''
    
    Note: We cannot use <i> for italics, as the expected behavior for italics specified by ''...'' in the title is that
    they will be inverted (i.e. unitalicized) in the resulting references.  In addition, <i> and '' tend to interact
    poorly under Mediawiki's HTML tidy.
    
    ]]
    
    local function safe_for_italics( str )
    	if not is_set(str) then
    		return str;
    	else
    		if str:sub(1,1) == "'" then str = "<span />" .. str; end
    		if str:sub(-1,-1) == "'" then str = str .. "<span />"; end
    		
    		-- Remove newlines as they break italics.
    		return str:gsub( '\n', ' ' );
    	end
    end
    
    --[[--------------------------< S A F E _ F O R _ U R L >------------------------------------------------------
    
    Escape sequences for content that will be used for URL descriptions
    
    ]]
    
    local function safe_for_url( str )
    	if str:match( "%[%[.-%]%]" ) ~= nil then 
    		table.insert( z.message_tail, { set_error( 'wikilink_in_url', {}, true ) } );
    	end
    	
    	return str:gsub( '[%[%]\n]', {	
    		['['] = '&#91;',
    		[']'] = '&#93;',
    		['\n'] = ' ' } );
    end
    
    --[[--------------------------< W R A P _ S T Y L E >----------------------------------------------------------
    
    Applies styling to various parameters.  Supplied string is wrapped using a message_list configuration taking one
    argument; protects italic styled parameters.  Additional text taken from citation_config.presentation - the reason
    this function is similar to but separate from wrap_msg().
    
    ]]
    
    local function wrap_style (key, str)
    	if not is_set( str ) then
    		return "";
    	elseif in_array( key, { 'italic-title', 'trans-italic-title' } ) then
    		str = safe_for_italics( str );
    	end
    
    	return substitute( cfg.presentation[key], {str} );
    end
    
    --[[--------------------------< E X T E R N A L _ L I N K >----------------------------------------------------
    
    Format an external link with error checking
    
    ]]
    
    local function external_link( URL, label, source )
    	local error_str = "";
    	if not is_set( label ) then
    		label = URL;
    		if is_set( source ) then
    			error_str = set_error( 'bare_url_missing_title', { wrap_style ('parameter', source) }, false, " " );
    		else
    			error( cfg.messages["bare_url_no_origin"] );
    		end			
    	end
    	if not check_url( URL ) then
    		error_str = set_error( 'bad_url', {wrap_style ('parameter', source)}, false, " " ) .. error_str;
    	end
    	return table.concat({ "[", URL, " ", safe_for_url( label ), "]", error_str });
    end
    
    --[[--------------------------< E X T E R N A L _ L I N K _ I D >----------------------------------------------
    
    Formats a wiki style external link
    
    ]]
    
    local function external_link_id(options)
    	local url_string = options.id;
    	if options.encode == true or options.encode == nil then
    		url_string = mw.uri.encode( url_string );
    	end
    	return mw.ustring.format( '[[%s|%s]]%s[%s%s%s %s]',
    		options.link, options.label, options.separator or "&nbsp;",
    		options.prefix, url_string, options.suffix or "",
    		mw.text.nowiki(options.id)
    	);
    end
    
    --[[--------------------------< D E P R E C A T E D _ P A R A M E T E R >--------------------------------------
    
    Categorize and emit an error message when the citation contains one or more deprecated parameters.  The function includes the
    offending parameter name to the error message.  Only one error message is emitted regardless of the number of deprecated
    parameters in the citation.
    
    ]]
    
    local page_in_deprecated_cat;													-- sticky flag so that the category is added only once
    local function deprecated_parameter(name)
    	if not page_in_deprecated_cat then
    		page_in_deprecated_cat = true;											-- note that we've added this category
    		table.insert( z.message_tail, { set_error( 'deprecated_params', {name}, true ) } );		-- add error message
    	end
    end
    
    --[[--------------------------< K E R N _ Q U O T E S >--------------------------------------------------------
    
    Apply kerning to open the space between the quote mark provided by the Module and a leading or trailing quote mark contained in a |title= or |chapter= parameter's value.
    This function will positive kern either single or double quotes:
    	"'Unkerned title with leading and trailing single quote marks'"
    	" 'Kerned title with leading and trailing single quote marks' " (in real life the kerning isn't as wide as this example)
    Double single quotes (italic or bold wikimarkup) are not kerned.
    
    Call this function for chapter titles, for website titles, etc; not for book titles.
    
    ]]
    
    local function kern_quotes (str)
    	local cap='';
    	local cap2='';
    	
    	cap, cap2 = str:match ("^([\"\'])([^\'].+)");								-- match leading double or single quote but not double single quotes
    	if is_set (cap) then
    		str = substitute (cfg.presentation['kern-left'], {cap, cap2});
    	end
    
    	cap, cap2 = str:match ("^(.+[^\'])([\"\'])$")
    	if is_set (cap) then
    		str = substitute (cfg.presentation['kern-right'], {cap, cap2});
    	end
    	return str;
    end
    
    --[[--------------------------< F O R M A T _ S C R I P T _ V A L U E >----------------------------------------
    
    |script-title= holds title parameters that are not written in Latin based scripts: Chinese, Japanese, Arabic, Hebrew, etc. These scripts should
    not be italicized and may be written right-to-left.  The value supplied by |script-title= is concatenated onto Title after Title has been wrapped
    in italic markup.
    
    Regardless of language, all values provided by |script-title= are wrapped in <bdi>...</bdi> tags to isolate rtl languages from the English left to right.
    
    |script-title= provides a unique feature.  The value in |script-title= may be prefixed with a two-character ISO639-1 language code and a colon:
    	|script-title=ja:*** *** (where * represents a Japanese character)
    Spaces between the two-character code and the colon and the colon and the first script character are allowed:
    	|script-title=ja : *** ***
    	|script-title=ja: *** ***
    	|script-title=ja :*** ***
    Spaces preceding the prefix are allowed: |script-title = ja:*** ***
    
    The prefix is checked for validity.  If it is a valid ISO639-1 language code, the lang attribute (lang="ja") is added to the <bdi> tag so that browsers can
    know the language the tag contains.  This may help the browser render the script more correctly.  If the prefix is invalid, the lang attribute
    is not added.  At this time there is no error message for this condition.
    
    Supports |script-title= and |script-chapter=
    
    TODO: error messages when prefix is invalid ISO639-1 code; when script_value has prefix but no script;
    ]]
    
    local function format_script_value (script_value)
    	local lang='';																-- initialize to empty string
    	local name;
    	if script_value:match('^%l%l%s*:') then										-- if first 3 non-space characters are script language prefix
    		lang = script_value:match('^(%l%l)%s*:%s*%S.*');						-- get the language prefix or nil if there is no script
    		if not is_set (lang) then
    			return '';															-- script_value was just the prefix so return empty string
    		end
    																				-- if we get this far we have prefix and script
    		name = mw.language.fetchLanguageName( lang, "en" );						-- get language name so that we can use it to categorize
    		if is_set (name) then													-- is prefix a proper ISO 639-1 language code?
    			script_value = script_value:gsub ('^%l%l%s*:%s*', '');				-- strip prefix from script
    																				-- is prefix one of these language codes?
    			if in_array (lang, {'ar', 'bg', 'bs', 'dv', 'el', 'fa', 'he', 'hy', 'ja', 'ka', 'ko', 'ku', 'mk', 'ps', 'ru', 'sd', 'sr', 'th', 'uk', 'ug', 'yi', 'zh'}) then
    				add_prop_cat ('script_with_name', {name, lang})
    			else
    				add_prop_cat ('script')
    			end
    			lang = ' lang="' .. lang .. '" ';									-- convert prefix into a lang attribute
    		else
    			lang = '';															-- invalid so set lang to empty string
    		end
    	end
    	script_value = substitute (cfg.presentation['bdi'], {lang, script_value});	-- isolate in case script is rtl
    
    	return script_value;
    end
    
    --[[--------------------------< S C R I P T _ C O N C A T E N A T E >------------------------------------------
    
    Initially for |title= and |script-title=, this function concatenates those two parameter values after the script value has been 
    wrapped in <bdi> tags.
    ]]
    
    local function script_concatenate (title, script)
    	if is_set (script) then
    		script = format_script_value (script);									-- <bdi> tags, lang atribute, categorization, etc; returns empty string on error
    		if is_set (script) then
    			title = title .. ' ' .. script;										-- concatenate title and script title
    		end
    	end
    	return title;
    end
    
    
    --[[--------------------------< W R A P _ M S G >--------------------------------------------------------------
    
    Applies additional message text to various parameter values. Supplied string is wrapped using a message_list
    configuration taking one argument.  Supports lower case text for {{citation}} templates.  Additional text taken
    from citation_config.messages - the reason this function is similar to but separate from wrap_style().
    
    ]]
    
    local function wrap_msg (key, str, lower)
    	if not is_set( str ) then
    		return "";
    	end
    	if true == lower then
    		local msg;
    		msg = cfg.messages[key]:lower();										-- set the message to lower case before 
    		return substitute( msg, str );										-- including template text
    	else
    		return substitute( cfg.messages[key], str );
    	end		
    end
    
    
    --[[-------------------------< I S _ A L I A S _ U S E D >-----------------------------------------------------
    
    This function is used by select_one() to determine if one of a list of alias parameters is in the argument list
    provided by the template.
    
    Input:
    	args – pointer to the arguments table from calling template
    	alias – one of the list of possible aliases in the aliases lists from Module:Citation/CS1/Configuration
    	index – for enumerated parameters, identifies which one
    	enumerated – true/false flag used choose how enumerated aliases are examined
    	value – value associated with an alias that has previously been selected; nil if not yet selected
    	selected – the alias that has previously been selected; nil if not yet selected
    	error_list – list of aliases that are duplicates of the alias already selected
    
    Returns:
    	value – value associated with alias we selected or that was previously selected or nil if an alias not yet selected
    	selected – the alias we selected or the alias that was previously selected or nil if an alias not yet selected
    
    ]]
    
    local function is_alias_used (args, alias, index, enumerated, value, selected, error_list)
    	if enumerated then															-- is this a test for an enumerated parameters?
    		alias = alias:gsub ('#', index);										-- replace '#' with the value in index
    	else
    		alias = alias:gsub ('#', '');											-- remove '#' if it exists
    	end
    
    	if is_set(args[alias]) then													-- alias is in the template's argument list
    		if value ~= nil and selected ~= alias then								-- if we have already selected one of the aliases
    			local skip;
    			for _, v in ipairs(error_list) do									-- spin through the error list to see if we've added this alias
    				if v == alias then
    					skip = true;
    					break;														-- has been added so stop looking 
    				end
    			end
    			if not skip then													-- has not been added so
    				table.insert( error_list, alias );								-- add error alias to the error list
    			end
    		else
    			value = args[alias];												-- not yet selected an alias, so select this one
    			selected = alias;
    		end
    	end
    	return value, selected;														-- return newly selected alias, or previously selected alias
    end
    
    
    --[[--------------------------< S E L E C T _ O N E >----------------------------------------------------------
    
    Chooses one matching parameter from a list of parameters to consider.  The list of parameters to consider is just
    names.  For parameters that may be enumerated, the position of the numerator in the parameter name is identified
    by the '#' so |author-last1= and |author1-last= are represented as 'author-last#' and 'author#-last'.
    
    Because enumerated parameter |<param>1= is an alias of |<param>= we must test for both possibilities.
    
    
    Generates an error if more than one match is present.
    
    ]]
    
    local function select_one( args, aliases_list, error_condition, index )
    	local value = nil;															-- the value assigned to the selected parameter
    	local selected = '';														-- the name of the parameter we have chosen
    	local error_list = {};
    
    	if index ~= nil then index = tostring(index); end
    
    	for _, alias in ipairs( aliases_list ) do									-- for each alias in the aliases list
    		if alias:match ('#') then												-- if this alias can be enumerated
    			if '1' == index then												-- when index is 1 test for enumerated and non-enumerated aliases
    				value, selected = is_alias_used (args, alias, index, false, value, selected, error_list);	-- first test for non-enumerated alias
    			end
    			value, selected = is_alias_used (args, alias, index, true, value, selected, error_list);		-- test for enumerated alias
    		else
    			value, selected = is_alias_used (args, alias, index, false, value, selected, error_list);		--test for non-enumerated alias
    		end
    	end
    
    	if #error_list > 0 and 'none' ~= error_condition then						-- for cases where this code is used outside of extract_names()
    		local error_str = "";
    		for _, k in ipairs( error_list ) do
    			if error_str ~= "" then error_str = error_str .. cfg.messages['parameter-separator'] end
    			error_str = error_str .. wrap_style ('parameter', k);
    		end
    		if #error_list > 1 then
    			error_str = error_str .. cfg.messages['parameter-final-separator'];
    		else
    			error_str = error_str .. cfg.messages['parameter-pair-separator'];
    		end
    		error_str = error_str .. wrap_style ('parameter', selected);
    		table.insert( z.message_tail, { set_error( error_condition, {error_str}, true ) } );
    	end
    	
    	return value, selected;
    end
    
    
    --[[--------------------------< F O R M A T _ C H A P T E R _ T I T L E >--------------------------------------
    
    Format the four chapter parameters: |script-chapter=, |chapter=, |trans-chapter=, and |chapter-url= into a single Chapter meta-
    parameter (chapter_url_source used for error messages).
    
    ]]
    
    local function format_chapter_title (scriptchapter, chapter, transchapter, chapterurl, chapter_url_source, no_quotes)
    	local chapter_error = '';
    	
    	if not is_set (chapter) then
    		chapter = '';															-- to be safe for concatenation
    	else
    		if false == no_quotes then
    			chapter = kern_quotes (chapter);										-- if necessary, separate chapter title's leading and trailing quote marks from Module provided quote marks
    			chapter = wrap_style ('quoted-title', chapter);
    		end
    	end
    
    	chapter = script_concatenate (chapter, scriptchapter)						-- <bdi> tags, lang atribute, categorization, etc; must be done after title is wrapped
    
    	if is_set (transchapter) then
    		transchapter = wrap_style ('trans-quoted-title', transchapter);
    		if is_set (chapter) then
    			chapter = chapter ..  ' ' .. transchapter;
    		else																	-- here when transchapter without chapter or script-chapter
    			chapter = transchapter;												-- 
    			chapter_error = ' ' .. set_error ('trans_missing_title', {'chapter'});
    		end
    	end
    
    	if is_set (chapterurl) then
    		chapter = external_link (chapterurl, chapter, chapter_url_source);		-- adds bare_url_missing_title error if appropriate
    	end
    
    	return chapter .. chapter_error;
    end
    
    --[[--------------------------< H A S _ I N V I S I B L E _ C H A R S >----------------------------------------
    
    This function searches a parameter's value for nonprintable or invisible characters.  The search stops at the
    first match.
    
    This function will detect the visible replacement character when it is part of the wikisource.
    
    Detects but ignores nowiki and math stripmarkers.  Also detects other named stripmarkers (gallery, math, pre, ref)
    and identifies them with a slightly different error message.  See also coins_cleanup().
    
    Detects but ignores the character pattern that results from the transclusion of {{'}} templates.
    
    Output of this function is an error message that identifies the character or the Unicode group, or the stripmarker
    that was detected along with its position (or, for multi-byte characters, the position of its first byte) in the
    parameter value.
    
    ]]
    
    local function has_invisible_chars (param, v)
    	local position = '';														-- position of invisible char or starting position of stripmarker
    	local dummy;																-- end of matching string; not used but required to hold end position when a capture is returned
    	local capture;																-- used by stripmarker detection to hold name of the stripmarker
    	local i=1;
    	local stripmarker, apostrophe;
    
    	while cfg.invisible_chars[i] do
    		local char=cfg.invisible_chars[i][1]									-- the character or group name
    		local pattern=cfg.invisible_chars[i][2]									-- the pattern used to find it
    		position, dummy, capture = mw.ustring.find (v, pattern)					-- see if the parameter value contains characters that match the pattern
    		
    		if position then
    --			if 'nowiki' == capture or 'math' == capture or ('ref' == capture and 'quote' == param) then 	-- nowiki, math, or quote param and ref stripmarker (not an error condition)
    			if 'nowiki' == capture or 'math' == capture then 					-- nowiki, math stripmarker (not an error condition)
    				stripmarker = true;												-- set a flag
    			elseif true == stripmarker and 'delete' == char then				-- because stripmakers begin and end with the delete char, assume that we've found one end of a stripmarker
    				position = nil;													-- unset
    			elseif 'apostrophe' == char then									-- apostrophe template uses &zwj;, hair space and zero-width space
    				apostrophe = true;
    			elseif true == apostrophe and in_array (char, {'zero width joiner', 'zero width space', 'hair space'}) then
    				position = nil;													-- unset
    			else
    				local err_msg;
    				if capture then
    					err_msg = capture .. ' ' .. char;
    				else
    					err_msg = char .. ' ' .. 'character';
    				end
    
    				table.insert( z.message_tail, { set_error( 'invisible_char', {err_msg, wrap_style ('parameter', param), position}, true ) } );	-- add error message
    				return;															-- and done with this parameter
    			end
    		end
    		i=i+1;																	-- bump our index
    	end
    end
    
    
    --[[--------------------------< A R G U M E N T _ W R A P P E R >----------------------------------------------
    
    Argument wrapper.  This function provides support for argument mapping defined in the configuration file so that
    multiple names can be transparently aliased to single internal variable.
    
    ]]
    
    local function argument_wrapper( args )
    	local origin = {};
    	
    	return setmetatable({
    		ORIGIN = function( self, k )
    			local dummy = self[k]; --force the variable to be loaded.
    			return origin[k];
    		end
    	},
    	{
    		__index = function ( tbl, k )
    			if origin[k] ~= nil then
    				return nil;
    			end
    			
    			local args, list, v = args, cfg.aliases[k];
    			
    			if type( list ) == 'table' then
    				v, origin[k] = select_one( args, list, 'redundant_parameters' );
    				if origin[k] == nil then
    					origin[k] = ''; -- Empty string, not nil
    				end
    			elseif list ~= nil then
    				v, origin[k] = args[list], list;
    			else
    				-- maybe let through instead of raising an error?
    				-- v, origin[k] = args[k], k;
    				error( cfg.messages['unknown_argument_map'] );
    			end
    			
    			-- Empty strings, not nil;
    			if v == nil then
    				v = cfg.defaults[k] or '';
    				origin[k] = '';
    			end
    			
    			tbl = rawset( tbl, k, v );
    			return v;
    		end,
    	});
    end
    
    --[[--------------------------< V A L I D A T E >--------------------------------------------------------------
    Looks for a parameter's name in the whitelist.
    
    Parameters in the whitelist can have three values:
    	true - active, supported parameters
    	false - deprecated, supported parameters
    	nil - unsupported parameters
    	
    ]]
    
    local function validate( name )
    	local name = tostring( name );
    	local state = whitelist.basic_arguments[ name ];
    	
    	-- Normal arguments
    	if true == state then return true; end		-- valid actively supported parameter
    	if false == state then
    		deprecated_parameter (name);				-- parameter is deprecated but still supported
    		return true;
    	end
    	
    	-- Arguments with numbers in them
    	name = name:gsub( "%d+", "#" );				-- replace digit(s) with # (last25 becomes last#
    	state = whitelist.numbered_arguments[ name ];
    	if true == state then return true; end		-- valid actively supported parameter
    	if false == state then
    		deprecated_parameter (name);				-- parameter is deprecated but still supported
    		return true;
    	end
    	
    	return false;								-- Not supported because not found or name is set to nil
    end
    
    
    -- Formats a wiki style internal link
    local function internal_link_id(options)
    	return mw.ustring.format( '[[%s|%s]]%s[[%s%s%s|%s]]',
    		options.link, options.label, options.separator or "&nbsp;",
    		options.prefix, options.id, options.suffix or "",
    		mw.text.nowiki(options.id)
    	);
    end
    
    
    --[[--------------------------< N O W R A P _ D A T E >--------------------------------------------------------
    
    When date is YYYY-MM-DD format wrap in nowrap span: <span ...>YYYY-MM-DD</span>.  When date is DD MMMM YYYY or is
    MMMM DD, YYYY then wrap in nowrap span: <span ...>DD MMMM</span> YYYY or <span ...>MMMM DD,</span> YYYY
    
    DOES NOT yet support MMMM YYYY or any of the date ranges.
    
    ]]
    
    local function nowrap_date (date)
    	local cap='';
    	local cap2='';
    
    	if date:match("^%d%d%d%d%-%d%d%-%d%d$") then
    		date = substitute (cfg.presentation['nowrap1'], date);
    	
    	elseif date:match("^%a+%s*%d%d?,%s+%d%d%d%d$") or date:match ("^%d%d?%s*%a+%s+%d%d%d%d$") then
    		cap, cap2 = string.match (date, "^(.*)%s+(%d%d%d%d)$");
    		date = substitute (cfg.presentation['nowrap2'], {cap, cap2});
    	end
    	
    	return date;
    end
    
    --[[--------------------------< IS _ V A L I D _ I S X N >-----------------------------------------------------
    
    ISBN-10 and ISSN validator code calculates checksum across all isbn/issn digits including the check digit. ISBN-13 is checked in check_isbn().
    If the number is valid the result will be 0. Before calling this function, issbn/issn must be checked for length and stripped of dashes,
    spaces and other non-isxn characters.
    
    ]]
    
    local function is_valid_isxn (isxn_str, len)
    	local temp = 0;
    	isxn_str = { isxn_str:byte(1, len) };	-- make a table of byte values '0' → 0x30 .. '9'  → 0x39, 'X' → 0x58
    	len = len+1;							-- adjust to be a loop counter
    	for i, v in ipairs( isxn_str ) do		-- loop through all of the bytes and calculate the checksum
    		if v == string.byte( "X" ) then		-- if checkdigit is X (compares the byte value of 'X' which is 0x58)
    			temp = temp + 10*( len - i );	-- it represents 10 decimal
    		else
    			temp = temp + tonumber( string.char(v) )*(len-i);
    		end
    	end
    	return temp % 11 == 0;					-- returns true if calculation result is zero
    end
    
    
    --[[--------------------------< IS _ V A L I D _ I S X N  _ 1 3 >----------------------------------------------
    
    ISBN-13 and ISMN validator code calculates checksum across all 13 isbn/ismn digits including the check digit.
    If the number is valid, the result will be 0. Before calling this function, isbn-13/ismn must be checked for length
    and stripped of dashes, spaces and other non-isxn-13 characters.
    
    ]]
    
    local function is_valid_isxn_13 (isxn_str)
    	local temp=0;
    	
    	isxn_str = { isxn_str:byte(1, 13) };										-- make a table of byte values '0' → 0x30 .. '9'  → 0x39
    	for i, v in ipairs( isxn_str ) do
    		temp = temp + (3 - 2*(i % 2)) * tonumber( string.char(v) );				-- multiply odd index digits by 1, even index digits by 3 and sum; includes check digit
    	end
    	return temp % 10 == 0;														-- sum modulo 10 is zero when isbn-13/ismn is correct
    end
    
    --[[--------------------------< C H E C K _ I S B N >------------------------------------------------------------
    
    Determines whether an ISBN string is valid
    
    ]]
    
    local function check_isbn( isbn_str )
    	if nil ~= isbn_str:match("[^%s-0-9X]") then return false; end		-- fail if isbn_str contains anything but digits, hyphens, or the uppercase X
    	isbn_str = isbn_str:gsub( "-", "" ):gsub( " ", "" );	-- remove hyphens and spaces
    	local len = isbn_str:len();
     
    	if len ~= 10 and len ~= 13 then
    		return false;
    	end
    
    	if len == 10 then
    		if isbn_str:match( "^%d*X?$" ) == nil then return false; end
    		return is_valid_isxn(isbn_str, 10);
    	else
    		local temp = 0;
    		if isbn_str:match( "^97[89]%d*$" ) == nil then return false; end		-- isbn13 begins with 978 or 979; ismn begins with 979
    		return is_valid_isxn_13 (isbn_str);
    	end
    end
    
    --[[--------------------------< C H E C K _ I S M N >------------------------------------------------------------
    
    Determines whether an ISMN string is valid.  Similar to isbn-13, ismn is 13 digits begining 979-0-... and uses the
    same check digit calculations.  See http://www.ismn-international.org/download/Web_ISMN_Users_Manual_2008-6.pdf
    section 2, pages 9–12.
    
    ]]
    
    local function ismn (id)
    	local handler = cfg.id_handlers['ISMN'];
    	local text;
    	local valid_ismn = true;
    
    	id=id:gsub( "[%s-–]", "" );													-- strip spaces, hyphens, and endashes from the ismn
    
    	if 13 ~= id:len() or id:match( "^9790%d*$" ) == nil then					-- ismn must be 13 digits and begin 9790
    		valid_ismn = false;
    	else
    		valid_ismn=is_valid_isxn_13 (id);										-- validate ismn
    	end
    
    --	text = internal_link_id({link = handler.link, label = handler.label,		-- use this (or external version) when there is some place to link to
    --		prefix=handler.prefix,id=id,separator=handler.separator, encode=handler.encode})
     
    	text="[[" .. handler.link .. "|" .. handler.label .. "]]" .. handler.separator .. id;		-- because no place to link to yet
    
    	if false == valid_ismn then
    		text = text .. ' ' .. set_error( 'bad_ismn' )							-- add an error message if the issn is invalid
    	end 
    	
    	return text;
    end
    
    --[[--------------------------< I S S N >----------------------------------------------------------------------
    
    Validate and format an issn.  This code fixes the case where an editor has included an ISSN in the citation but has separated the two groups of four
    digits with a space.  When that condition occurred, the resulting link looked like this:
    
    	|issn=0819 4327 gives: [http://www.worldcat.org/issn/0819 4327 0819 4327]  -- can't have spaces in an external link
    	
    This code now prevents that by inserting a hyphen at the issn midpoint.  It also validates the issn for length and makes sure that the checkdigit agrees
    with the calculated value.  Incorrect length (8 digits), characters other than 0-9 and X, or checkdigit / calculated value mismatch will all cause a check issn
    error message.  The issn is always displayed with a hyphen, even if the issn was given as a single group of 8 digits.
    
    ]]
    
    local function issn(id)
    	local issn_copy = id;		-- save a copy of unadulterated issn; use this version for display if issn does not validate
    	local handler = cfg.id_handlers['ISSN'];
    	local text;
    	local valid_issn = true;
    
    	id=id:gsub( "[%s-–]", "" );									-- strip spaces, hyphens, and endashes from the issn
    
    	if 8 ~= id:len() or nil == id:match( "^%d*X?$" ) then		-- validate the issn: 8 digits long, containing only 0-9 or X in the last position
    		valid_issn=false;										-- wrong length or improper character
    	else
    		valid_issn=is_valid_isxn(id, 8);						-- validate issn
    	end
    
    	if true == valid_issn then
    		id = string.sub( id, 1, 4 ) .. "-" .. string.sub( id, 5 );	-- if valid, display correctly formatted version
    	else
    		id = issn_copy;											-- if not valid, use the show the invalid issn with error message
    	end
    	
    	text = external_link_id({link = handler.link, label = handler.label,
    		prefix=handler.prefix,id=id,separator=handler.separator, encode=handler.encode})
     
    	if false == valid_issn then
    		text = text .. ' ' .. set_error( 'bad_issn' )			-- add an error message if the issn is invalid
    	end 
    	
    	return text
    end
    
    --[[--------------------------< A M A Z O N >------------------------------------------------------------------
    
    Formats a link to Amazon.  Do simple error checking: asin must be mix of 10 numeric or uppercase alpha
    characters.  If a mix, first character must be uppercase alpha; if all numeric, asins must be 10-digit
    isbn. If 10-digit isbn, add a maintenance category so a bot or awb script can replace |asin= with |isbn=.
    Error message if not 10 characters, if not isbn10, if mixed and first character is a digit.
    
    ]]
    
    local function amazon(id, domain)
    	local err_cat = ""
    
    	if not id:match("^[%d%u][%d%u][%d%u][%d%u][%d%u][%d%u][%d%u][%d%u][%d%u][%d%u]$") then
    		err_cat =  ' ' .. set_error ('bad_asin');								-- asin is not a mix of 10 uppercase alpha and numeric characters
    	else
    		if id:match("^%d%d%d%d%d%d%d%d%d[%dX]$") then								-- if 10-digit numeric (or 9 digits with terminal X)
    			if check_isbn( id ) then												-- see if asin value is isbn10
    				add_maint_cat ('ASIN');
    			elseif not is_set (err_cat) then
    				err_cat =  ' ' .. set_error ('bad_asin');						-- asin is not isbn10
    			end
    		elseif not id:match("^%u[%d%u]+$") then
    			err_cat =  ' ' .. set_error ('bad_asin');							-- asin doesn't begin with uppercase alpha
    		end
    	end
    	if not is_set(domain) then 
    		domain = "com";
    	elseif in_array (domain, {'jp', 'uk'}) then			-- Japan, United Kingdom
    		domain = "co." .. domain;
    	elseif in_array (domain, {'au', 'br', 'mx'}) then	-- Australia, Brazil, Mexico
    		domain = "com." .. domain;
    	end
    	local handler = cfg.id_handlers['ASIN'];
    	return external_link_id({link=handler.link,
    		label=handler.label, prefix=handler.prefix .. domain .. "/dp/",
    		id=id, encode=handler.encode, separator = handler.separator}) .. err_cat;
    end
    
    --[[--------------------------< A R X I V >--------------------------------------------------------------------
    
    See: http://arxiv.org/help/arxiv_identifier
    
    format and error check arXiv identifier.  There are three valid forms of the identifier:
    the first form, valid only between date codes 9108 and 0703 is:
    	arXiv:<archive>.<class>/<date code><number><version>
    where:
    	<archive> is a string of alpha characters - may be hyphenated; no other punctuation
    	<class> is a string of alpha characters - may be hyphenated; no other punctuation
    	<date code> is four digits in the form YYMM where YY is the last two digits of the four-digit year and MM is the month number January = 01
    		first digit of YY for this form can only 9 and 0
    	<number> is a three-digit number
    	<version> is a 1 or more digit number preceded with a lowercase v; no spaces (undocumented)
    	
    the second form, valid from April 2007 through December 2014 is:
    	arXiv:<date code>.<number><version>
    where:
    	<date code> is four digits in the form YYMM where YY is the last two digits of the four-digit year and MM is the month number January = 01
    	<number> is a four-digit number
    	<version> is a 1 or more digit number preceded with a lowercase v; no spaces
    
    the third form, valid from January 2015 is:
    	arXiv:<date code>.<number><version>
    where:
    	<date code> and <version> are as defined for 0704-1412
    	<number> is a five-digit number
    ]]
    
    local function arxiv (id, class)
    	local handler = cfg.id_handlers['ARXIV'];
    	local year, month, version;
    	local err_cat = '';
    	local text;
    	
    	if id:match("^%a[%a%.%-]+/[90]%d[01]%d%d%d%d$") or id:match("^%a[%a%.%-]+/[90]%d[01]%d%d%d%dv%d+$") then	-- test for the 9108-0703 format w/ & w/o version
    		year, month = id:match("^%a[%a%.%-]+/([90]%d)([01]%d)%d%d%d[v%d]*$");
    		year = tonumber(year);
    		month = tonumber(month);
    		if ((not (90 < year or 8 > year)) or (1 > month or 12 < month)) or		-- if invalid year or invalid month
    			((91 == year and 7 > month) or (7 == year and 3 < month)) then		-- if years ok, are starting and ending months ok?
    				err_cat = ' ' .. set_error( 'bad_arxiv' );						-- set error message
    		end
    	elseif id:match("^%d%d[01]%d%.%d%d%d%d$") or id:match("^%d%d[01]%d%.%d%d%d%dv%d+$") then	-- test for the 0704-1412 w/ & w/o version
    		year, month = id:match("^(%d%d)([01]%d)%.%d%d%d%d[v%d]*$");
    		year = tonumber(year);
    		month = tonumber(month);
    		if ((7 > year) or (14 < year) or (1 > month or 12 < month)) or			-- is year invalid or is month invalid? (doesn't test for future years)
    			((7 == year) and (4 > month)) then --or									-- when year is 07, is month invalid (before April)?
    				err_cat = ' ' .. set_error( 'bad_arxiv' );						-- set error message
    		end
    	elseif id:match("^%d%d[01]%d%.%d%d%d%d%d$") or id:match("^%d%d[01]%d%.%d%d%d%d%dv%d+$") then	-- test for the 1501- format w/ & w/o version
    		year, month = id:match("^(%d%d)([01]%d)%.%d%d%d%d%d[v%d]*$");
    		year = tonumber(year);
    		month = tonumber(month);
    		if ((15 > year) or (1 > month or 12 < month)) then						-- is year invalid or is month invalid? (doesn't test for future years)
    			err_cat = ' ' .. set_error( 'bad_arxiv' );							-- set error message
    		end
    	else
    		err_cat = ' ' .. set_error( 'bad_arxiv' );								-- arXiv id doesn't match any format
    	end
    
    	text = external_link_id({link = handler.link, label = handler.label,
    			prefix=handler.prefix,id=id,separator=handler.separator, encode=handler.encode}) .. err_cat;
    
    	if is_set (class) then
    		class = ' [[' .. '//arxiv.org/archive/' .. class .. ' ' .. class .. ']]';	-- external link within square brackets, not wikilink
    	else
    		class = '';																-- empty string for concatenation
    	end
    	
    	return text .. class;
    end
    
    --[[
    lccn normalization (http://www.loc.gov/marc/lccn-namespace.html#normalization)
    1. Remove all blanks.
    2. If there is a forward slash (/) in the string, remove it, and remove all characters to the right of the forward slash.
    3. If there is a hyphen in the string:
    	a. Remove it.
    	b. Inspect the substring following (to the right of) the (removed) hyphen. Then (and assuming that steps 1 and 2 have been carried out):
    		1. All these characters should be digits, and there should be six or less. (not done in this function)
    		2. If the length of the substring is less than 6, left-fill the substring with zeroes until the length is six.
    
    Returns a normalized lccn for lccn() to validate.  There is no error checking (step 3.b.1) performed in this function.
    ]]
    
    local function normalize_lccn (lccn)
    	lccn = lccn:gsub ("%s", "");									-- 1. strip whitespace
    
    	if nil ~= string.find (lccn,'/') then
    		lccn = lccn:match ("(.-)/");								-- 2. remove forward slash and all character to the right of it
    	end
    
    	local prefix
    	local suffix
    	prefix, suffix = lccn:match ("(.+)%-(.+)");						-- 3.a remove hyphen by splitting the string into prefix and suffix
    
    	if nil ~= suffix then											-- if there was a hyphen
    		suffix=string.rep("0", 6-string.len (suffix)) .. suffix;	-- 3.b.2 left fill the suffix with 0s if suffix length less than 6
    		lccn=prefix..suffix;										-- reassemble the lccn
    	end
    	
    	return lccn;
    	end
    
    --[[
    Format LCCN link and do simple error checking.  LCCN is a character string 8-12 characters long. The length of the LCCN dictates the character type of the first 1-3 characters; the
    rightmost eight are always digits. http://info-uri.info/registry/OAIHandler?verb=GetRecord&metadataPrefix=reg&identifier=info:lccn/
    
    length = 8 then all digits
    length = 9 then lccn[1] is lower case alpha
    length = 10 then lccn[1] and lccn[2] are both lower case alpha or both digits
    length = 11 then lccn[1] is lower case alpha, lccn[2] and lccn[3] are both lower case alpha or both digits
    length = 12 then lccn[1] and lccn[2] are both lower case alpha
    
    ]]
    
    local function lccn(lccn)
    	local handler = cfg.id_handlers['LCCN'];
    	local err_cat =  '';								-- presume that LCCN is valid
    	local id = lccn;									-- local copy of the lccn
    
    	id = normalize_lccn (id);							-- get canonical form (no whitespace, hyphens, forward slashes)
    	local len = id:len();								-- get the length of the lccn
    
    	if 8 == len then
    		if id:match("[^%d]") then						-- if LCCN has anything but digits (nil if only digits)
    			err_cat = ' ' .. set_error( 'bad_lccn' );	-- set an error message
    		end
    	elseif 9 == len then								-- LCCN should be adddddddd
    		if nil == id:match("%l%d%d%d%d%d%d%d%d") then			-- does it match our pattern?
    			err_cat = ' ' .. set_error( 'bad_lccn' );	-- set an error message
    		end
    	elseif 10 == len then								-- LCCN should be aadddddddd or dddddddddd
    		if id:match("[^%d]") then							-- if LCCN has anything but digits (nil if only digits) ...
    			if nil == id:match("^%l%l%d%d%d%d%d%d%d%d") then	-- ... see if it matches our pattern
    				err_cat = ' ' .. set_error( 'bad_lccn' );	-- no match, set an error message
    			end
    		end
    	elseif 11 == len then								-- LCCN should be aaadddddddd or adddddddddd
    		if not (id:match("^%l%l%l%d%d%d%d%d%d%d%d") or id:match("^%l%d%d%d%d%d%d%d%d%d%d")) then	-- see if it matches one of our patterns
    			err_cat = ' ' .. set_error( 'bad_lccn' );	-- no match, set an error message
    		end
    	elseif 12 == len then								-- LCCN should be aadddddddddd
    		if not id:match("^%l%l%d%d%d%d%d%d%d%d%d%d") then	-- see if it matches our pattern
    			err_cat = ' ' .. set_error( 'bad_lccn' );	-- no match, set an error message
    		end
    	else
    		err_cat = ' ' .. set_error( 'bad_lccn' );		-- wrong length, set an error message
    	end
    
    	if not is_set (err_cat) and nil ~= lccn:find ('%s') then
    		err_cat = ' ' .. set_error( 'bad_lccn' );		-- lccn contains a space, set an error message
    	end
    
    	return external_link_id({link = handler.link, label = handler.label,
    			prefix=handler.prefix,id=lccn,separator=handler.separator, encode=handler.encode}) .. err_cat;
    end
    
    --[[
    Format PMID and do simple error checking.  PMIDs are sequential numbers beginning at 1 and counting up.  This code checks the PMID to see that it
    contains only digits and is less than test_limit; the value in local variable test_limit will need to be updated periodically as more PMIDs are issued.
    ]]
    
    local function pmid(id)
    	local test_limit = 30000000;						-- update this value as PMIDs approach
    	local handler = cfg.id_handlers['PMID'];
    	local err_cat =  '';								-- presume that PMID is valid
    	
    	if id:match("[^%d]") then							-- if PMID has anything but digits
    		err_cat = ' ' .. set_error( 'bad_pmid' );		-- set an error message
    	else												-- PMID is only digits
    		local id_num = tonumber(id);					-- convert id to a number for range testing
    		if 1 > id_num or test_limit < id_num then		-- if PMID is outside test limit boundaries
    			err_cat = ' ' .. set_error( 'bad_pmid' );	-- set an error message
    		end
    	end
    	
    	return external_link_id({link = handler.link, label = handler.label,
    			prefix=handler.prefix,id=id,separator=handler.separator, encode=handler.encode}) .. err_cat;
    end
    
    --[[--------------------------< I S _ E M B A R G O E D >------------------------------------------------------
    
    Determines if a PMC identifier's online version is embargoed. Compares the date in |embargo= against today's date.  If embargo date is
    in the future, returns the content of |embargo=; otherwise, returns and empty string because the embargo has expired or because
    |embargo= was not set in this cite.
    
    ]]
    
    local function is_embargoed (embargo)
    	if is_set (embargo) then
    		local lang = mw.getContentLanguage();
    		local good1, embargo_date, good2, todays_date;
    		good1, embargo_date = pcall( lang.formatDate, lang, 'U', embargo );
    		good2, todays_date = pcall( lang.formatDate, lang, 'U' );
    	
    		if good1 and good2 then													-- if embargo date and today's date are good dates
    			if tonumber( embargo_date ) >= tonumber( todays_date ) then			-- is embargo date is in the future?
    				return embargo;													-- still embargoed
    			else
    				add_maint_cat ('embargo')
    				return '';														-- unset because embargo has expired
    			end
    		end
    	end
    	return '';																	-- |embargo= not set return empty string
    end
    
    --[[--------------------------< P M C >------------------------------------------------------------------------
    
    Format a PMC, do simple error checking, and check for embargoed articles.
    
    The embargo parameter takes a date for a value. If the embargo date is in the future the PMC identifier will not
    be linked to the article.  If the embargo date is today or in the past, or if it is empty or omitted, then the
    PMC identifier is linked to the article through the link at cfg.id_handlers['PMC'].prefix.
    
    PMC embargo date testing is done in function is_embargoed () which is called earlier because when the citation
    has |pmc=<value> but does not have a |url= then |title= is linked with the PMC link.  Function is_embargoed ()
    returns the embargo date if the PMC article is still embargoed, otherwise it returns an empty string.
    
    PMCs are sequential numbers beginning at 1 and counting up.  This code checks the PMC to see that it contains only digits and is less
    than test_limit; the value in local variable test_limit will need to be updated periodically as more PMCs are issued.
    
    ]]
    
    local function pmc(id, embargo)
    	local test_limit = 5000000;							-- update this value as PMCs approach
    	local handler = cfg.id_handlers['PMC'];
    	local err_cat =  '';								-- presume that PMC is valid
    	
    	local text;
    
    	if id:match("[^%d]") then							-- if PMC has anything but digits
    		err_cat = ' ' .. set_error( 'bad_pmc' );			-- set an error message
    	else												-- PMC is only digits
    		local id_num = tonumber(id);					-- convert id to a number for range testing
    		if 1 > id_num or test_limit < id_num then		-- if PMC is outside test limit boundaries
    			err_cat = ' ' .. set_error( 'bad_pmc' );		-- set an error message
    		end
    	end
    	
    	if is_set (embargo) then													-- is PMC is still embargoed?
    		text="[[" .. handler.link .. "|" .. handler.label .. "]]:" .. handler.separator .. id .. err_cat;	-- still embargoed so no external link
    	else
    		text = external_link_id({link = handler.link, label = handler.label,			-- no embargo date or embargo has expired, ok to link to article
    			prefix=handler.prefix,id=id,separator=handler.separator, encode=handler.encode}) .. err_cat;
    	end
    	return text;
    end
    
    -- Formats a DOI and checks for DOI errors.
    
    -- DOI names contain two parts: prefix and suffix separated by a forward slash.
    --  Prefix: directory indicator '10.' followed by a registrant code
    --  Suffix: character string of any length chosen by the registrant
    
    -- This function checks a DOI name for: prefix/suffix.  If the doi name contains spaces or endashes,
    -- or, if it ends with a period or a comma, this function will emit a bad_doi error message.
    
    -- DOI names are case-insensitive and can incorporate any printable Unicode characters so the test for spaces, endash,
    -- and terminal punctuation may not be technically correct but it appears, that in practice these characters are rarely if ever used in doi names.
    
    local function doi(id, inactive)
    	local cat = ""
    	local handler = cfg.id_handlers['DOI'];
    	
    	local text;
    	if is_set(inactive) then
    		local inactive_year = inactive:match("%d%d%d%d") or '';		-- try to get the year portion from the inactive date
    		text = "[[" .. handler.link .. "|" .. handler.label .. "]]:" .. id;
    		if is_set(inactive_year) then
    			table.insert( z.error_categories, "Pages with DOIs inactive since " .. inactive_year );
    		else
    			table.insert( z.error_categories, "Pages with inactive DOIs" );	-- when inactive doesn't contain a recognizable year
    		end
    		inactive = " (" .. cfg.messages['inactive'] .. " " .. inactive .. ")" 
    	else 
    		text = external_link_id({link = handler.link, label = handler.label,
    			prefix=handler.prefix,id=id,separator=handler.separator, encode=handler.encode})
    		inactive = "" 
    	end
    
    	if nil == id:match("^10%.[^%s–]-/[^%s–]-[^%.,]$") then	-- doi must begin with '10.', must contain a fwd slash, must not contain spaces or endashes, and must not end with period or comma
    		cat = ' ' .. set_error( 'bad_doi' );
    	end
    	return text .. inactive .. cat 
    end
    
    
    --[[--------------------------< O P E N L I B R A R Y >--------------------------------------------------------
    
    Formats an OpenLibrary link, and checks for associated errors.
    
    ]]
    local function openlibrary(id)
    	local code = id:match("^%d+([AMW])$");										-- only digits followed by 'A', 'M', or 'W'
    	local handler = cfg.id_handlers['OL'];
    
    	if ( code == "A" ) then
    		return external_link_id({link=handler.link, label=handler.label,
    			prefix=handler.prefix .. 'authors/OL',
    			id=id, separator=handler.separator,	encode = handler.encode})
    	elseif ( code == "M" ) then
    		return external_link_id({link=handler.link, label=handler.label,
    			prefix=handler.prefix .. 'books/OL',
    			id=id, separator=handler.separator,	encode = handler.encode})
    	elseif ( code == "W" ) then
    		return external_link_id({link=handler.link, label=handler.label,
    			prefix=handler.prefix .. 'works/OL',
    			id=id, separator=handler.separator,	encode = handler.encode})
    	else
    		return external_link_id({link=handler.link, label=handler.label,
    			prefix=handler.prefix .. 'OL',
    			id=id, separator=handler.separator,	encode = handler.encode}) .. ' ' .. set_error( 'bad_ol' );
    	end
    end
    
    
    --[[--------------------------< M E S S A G E _ I D >----------------------------------------------------------
    
    Validate and format a usenet message id.  Simple error checking, looks for 'id-left@id-right' not enclosed in
    '<' and/or '>' angle brackets.
    
    ]]
    
    local function message_id (id)
    	local handler = cfg.id_handlers['USENETID'];
    
    	text = external_link_id({link = handler.link, label = handler.label,
    		prefix=handler.prefix,id=id,separator=handler.separator, encode=handler.encode})
     
    	if not id:match('^.+@.+$') or not id:match('^[^<].*[^>]$')then				-- doesn't have '@' or has one or first or last character is '< or '>'
    		text = text .. ' ' .. set_error( 'bad_message_id' )						-- add an error message if the message id is invalid
    	end 
    	
    	return text
    end
    
    --[[--------------------------< S E T _ T I T L E T Y P E >----------------------------------------------------
    
    This function sets default title types (equivalent to the citation including |type=<default value>) for those templates that have defaults.
    Also handles the special case where it is desirable to omit the title type from the rendered citation (|type=none).
    
    ]]
    
    local function set_titletype (cite_class, title_type)
    	if is_set(title_type) then
    		if "none" == title_type then
    			title_type = "";													-- if |type=none then type parameter not displayed
    		end
    		return title_type;														-- if |type= has been set to any other value use that value
    	end
    
    	return cfg.title_types [cite_class] or '';									-- set template's default title type; else empty string for concatenation
    end
    
    --[[--------------------------< C L E A N _ I S B N >----------------------------------------------------------
    
    Removes irrelevant text and dashes from ISBN number
    Similar to that used for Special:BookSources
    
    ]]
    
    local function clean_isbn( isbn_str )
    	return isbn_str:gsub( "[^-0-9X]", "" );
    end
    
    --[[--------------------------< E S C A P E _ L U A _ M A G I C _ C H A R S >----------------------------------
    
    Returns a string where all of lua's magic characters have been escaped.  This is important because functions like
    string.gsub() treat their pattern and replace strings as patterns, not literal strings.
    ]]
    local function escape_lua_magic_chars (argument)
    	argument = argument:gsub("%%", "%%%%");										-- replace % with %%
    	argument = argument:gsub("([%^%$%(%)%.%[%]%*%+%-%?])", "%%%1");				-- replace all other lua magic pattern characters
    	return argument;
    end
    
    --[[--------------------------< S T R I P _ A P O S T R O P H E _ M A R K U P >--------------------------------
    
    Strip wiki italic and bold markup from argument so that it doesn't contaminate COinS metadata.
    This function strips common patterns of apostrophe markup.  We presume that editors who have taken the time to
    markup a title have, as a result, provided valid markup. When they don't, some single apostrophes are left behind.
    
    ]]
    
    local function strip_apostrophe_markup (argument)
    	if not is_set (argument) then return argument; end
    
    	while true do
    		if argument:match ("%'%'%'%'%'") then									-- bold italic (5)
    			argument=argument:gsub("%'%'%'%'%'", "");							-- remove all instances of it
    		elseif argument:match ("%'%'%'%'") then									-- italic start and end without content (4)
    			argument=argument:gsub("%'%'%'%'", "");
    		elseif argument:match ("%'%'%'") then									-- bold (3)
    			argument=argument:gsub("%'%'%'", "");
    		elseif argument:match ("%'%'") then										-- italic (2)
    			argument=argument:gsub("%'%'", "");
    		else
    			break;
    		end
    	end
    	return argument;															-- done
    end
    
    --[[--------------------------< M A K E _ C O I N S _ T I T L E >----------------------------------------------
    
    Makes a title for COinS from Title and / or ScriptTitle (or any other name-script pairs)
    
    Apostrophe markup (bold, italics) is stripped from each value so that the COinS metadata isn't correupted with strings
    of %27%27...
    ]]
    
    local function make_coins_title (title, script)
    	if is_set (title) then
    		title = strip_apostrophe_markup (title);								-- strip any apostrophe markup
    	else
    		title='';																-- if not set, make sure title is an empty string
    	end
    	if is_set (script) then
    		script = script:gsub ('^%l%l%s*:%s*', '');								-- remove language prefix if present (script value may now be empty string)
    		script = strip_apostrophe_markup (script);								-- strip any apostrophe markup
    	else
    		script='';																-- if not set, make sure script is an empty string
    	end
    	if is_set (title) and is_set (script) then
    		script = ' ' .. script;													-- add a space before we concatenate
    	end
    	return title .. script;														-- return the concatenation
    end
    
    --[[--------------------------< G E T _ C O I N S _ P A G E S >------------------------------------------------
    
    Extract page numbers from external wikilinks in any of the |page=, |pages=, or |at= parameters for use in COinS.
    
    ]]
    
    local function get_coins_pages (pages)
    	local pattern;
    	if not is_set (pages) then return pages; end								-- if no page numbers then we're done
    	
    	while true do
    		pattern = pages:match("%[(%w*:?//[^ ]+%s+)[%w%d].*%]");					-- pattern is the opening bracket, the url and following space(s): "[url "
    		if nil == pattern then break; end										-- no more urls
    		pattern = escape_lua_magic_chars (pattern);								-- pattern is not a literal string; escape lua's magic pattern characters
    		pages = pages:gsub(pattern, "");										-- remove as many instances of pattern as possible
    	end
    	pages = pages:gsub("[%[%]]", "");											-- remove the brackets
    	pages = pages:gsub("–", "-" );							-- replace endashes with hyphens
    	pages = pages:gsub("&%w+;", "-" );						-- and replace html entities (&ndash; etc.) with hyphens; do we need to replace numerical entities like &#32; and the like?
    	return pages;
    end
    
    -- Gets the display text for a wikilink like [[A|B]] or [[B]] gives B
    local function remove_wiki_link( str )
    	return (str:gsub( "%[%[([^%[%]]*)%]%]", function(l)
    		return l:gsub( "^[^|]*|(.*)$", "%1" ):gsub("^%s*(.-)%s*$", "%1");
    	end));
    end
    
    -- Converts a hyphen to a dash
    local function hyphen_to_dash( str )
    	if not is_set(str) or str:match( "[%[%]{}<>]" ) ~= nil then
    		return str;
    	end	
    	return str:gsub( '-', '–' );
    end
    
    --[[--------------------------< S A F E _ J O I N >------------------------------------------------------------
    
    Joins a sequence of strings together while checking for duplicate separation characters.
    
    ]]
    
    local function safe_join( tbl, duplicate_char )
    	--[[
    	Note: we use string functions here, rather than ustring functions.
    	
    	This has considerably faster performance and should work correctly as 
    	long as the duplicate_char is strict ASCII.  The strings
    	in tbl may be ASCII or UTF8.
    	]]
    	
    	local str = '';																-- the output string
    	local comp = '';															-- what does 'comp' mean?
    	local end_chr = '';
    	local trim;
    	for _, value in ipairs( tbl ) do
    		if value == nil then value = ''; end
    		
    		if str == '' then														-- if output string is empty
    			str = value;														-- assign value to it (first time through the loop)
    		elseif value ~= '' then
    			if value:sub(1,1) == '<' then										-- Special case of values enclosed in spans and other markup.
    				comp = value:gsub( "%b<>", "" );								-- remove html markup (<span>string</span> -> string)
    			else
    				comp = value;
    			end
    																				-- typically duplicate_char is sepc
    			if comp:sub(1,1) == duplicate_char then								-- is first charactier same as duplicate_char? why test first character?
    																				--   Because individual string segments often (always?) begin with terminal punct for th
    																				--   preceding segment: 'First element' .. 'sepc next element' .. etc?
    				trim = false;
    				end_chr = str:sub(-1,-1);										-- get the last character of the output string
    				-- str = str .. "<HERE(enchr=" .. end_chr.. ")"					-- debug stuff?
    				if end_chr == duplicate_char then								-- if same as separator
    					str = str:sub(1,-2);										-- remove it
    				elseif end_chr == "'" then										-- if it might be wikimarkup
    					if str:sub(-3,-1) == duplicate_char .. "''" then			-- if last three chars of str are sepc'' 
    						str = str:sub(1, -4) .. "''";							-- remove them and add back ''
    					elseif str:sub(-5,-1) == duplicate_char .. "]]''" then		-- if last five chars of str are sepc]]'' 
    						trim = true;											-- why? why do this and next differently from previous?
    					elseif str:sub(-4,-1) == duplicate_char .. "]''" then		-- if last four chars of str are sepc]'' 
    						trim = true;											-- same question
    					end
    				elseif end_chr == "]" then										-- if it might be wikimarkup
    					if str:sub(-3,-1) == duplicate_char .. "]]" then			-- if last three chars of str are sepc]] wikilink 
    						trim = true;
    					elseif str:sub(-2,-1) == duplicate_char .. "]" then			-- if last two chars of str are sepc] external link
    						trim = true;
    					elseif str:sub(-4,-1) == duplicate_char .. "'']" then		-- normal case when |url=something & |title=Title.
    						trim = true;
    					end
    				elseif end_chr == " " then										-- if last char of output string is a space
    					if str:sub(-2,-1) == duplicate_char .. " " then				-- if last two chars of str are <sepc><space>
    						str = str:sub(1,-3);									-- remove them both
    					end
    				end
    
    				if trim then
    					if value ~= comp then 										-- value does not equal comp when value contains html markup
    						local dup2 = duplicate_char;
    						if dup2:match( "%A" ) then dup2 = "%" .. dup2; end		-- if duplicate_char not a letter then escape it
    						
    						value = value:gsub( "(%b<>)" .. dup2, "%1", 1 )			-- remove duplicate_char if it follows html markup
    					else
    						value = value:sub( 2, -1 );								-- remove duplicate_char when it is first character
    					end
    				end
    			end
    			str = str .. value;													--add it to the output string
    		end
    	end
    	return str;
    end  
    
    --[[--------------------------< I S _ G O O D _ V A N C _ N A M E >--------------------------------------------
    
    For Vancouver Style, author/editor names are supposed to be rendered in Latin (read ASCII) characters.  When a name
    uses characters that contain diacritical marks, those characters are to converted to the corresponding Latin character.
    When a name is written using a non-Latin alphabet or logogram, that name is to be transliterated into Latin characters.
    These things are not currently possible in this module so are left to the editor to do.
    
    This test allows |first= and |last= names to contain any of the letters defined in the four Unicode Latin character sets
    	[http://www.unicode.org/charts/PDF/U0000.pdf C0 Controls and Basic Latin] 0041–005A, 0061–007A
    	[http://www.unicode.org/charts/PDF/U0080.pdf C1 Controls and Latin-1 Supplement] 00C0–00D6, 00D8–00F6, 00F8–00FF
    	[http://www.unicode.org/charts/PDF/U0100.pdf Latin Extended-A] 0100–017F
    	[http://www.unicode.org/charts/PDF/U0180.pdf Latin Extended-B] 0180–01BF, 01C4–024F
    
    |lastn= also allowed to contain hyphens, spaces, and apostrophes. (http://www.ncbi.nlm.nih.gov/books/NBK7271/box/A35029/)
    |firstn= also allowed to contain hyphens, spaces, apostrophes, and periods
    
    At the time of this writing, I had to write the 'if nil == mw.ustring.find ...' test ouside of the code editor and paste it here
    because the code editor gets confused between character insertion point and cursor position.
    
    ]]
    
    local function is_good_vanc_name (last, first)
    	if nil == mw.ustring.find (last, "^[A-Za-zÀ-ÖØ-öø-ƿDŽ-ɏ%-%s%']*$") or nil == mw.ustring.find (first, "^[A-Za-zÀ-ÖØ-öø-ƿDŽ-ɏ%-%s%'%.]*$") then
    		add_vanc_error ();
    		return false;															-- not a string of latin characters; Vancouver required Romanization
    	end;
    	return true;
    end
    
    --[[--------------------------< R E D U C E _ T O _ I N I T I A L S >------------------------------------------
    
    Attempts to convert names to initials in support of |name-list-format=vanc.  
    
    Names in |firstn= may be separated by spaces or hyphens, or for initials, a period. See http://www.ncbi.nlm.nih.gov/books/NBK7271/box/A35062/.
    
    Vancouver style requires family rank designations (Jr, II, III, etc) to be rendered as Jr, 2nd, 3rd, etc.  This form is not
    currently supported by this code so correctly formed names like Smith JL 2nd are converted to Smith J2. See http://www.ncbi.nlm.nih.gov/books/NBK7271/box/A35085/.
    
    This function uses ustring functions because firstname initials may be any of the unicode Latin characters accepted by is_good_vanc_name ().
    
    ]]
    
    local function reduce_to_initials(first)
    	if mw.ustring.match(first, "^%u%u$") then return first end;					-- when first contains just two upper-case letters, nothing to do
    	local initials = {}
    	local i = 0;																-- counter for number of initials
    	for word in mw.ustring.gmatch(first, "[^%s%.%-]+") do						-- names separated by spaces, hyphens, or periods
    		table.insert(initials, mw.ustring.sub(word,1,1))						-- Vancouver format does not include full stops.
    		i = i + 1;																-- bump the counter 
    		if 2 <= i then break; end												-- only two initials allowed in Vancouver system; if 2, quit
    	end
    	return table.concat(initials)												-- Vancouver format does not include spaces.
    end
    
    --[[--------------------------< L I S T  _ P E O P L E >-------------------------------------------------------
    
    Formats a list of people (e.g. authors / editors) 
    
    ]]
    
    local function list_people(control, people, etal, list_name)					-- TODO: why is list_name here?  not used in this function
    	local sep;
    	local namesep;
    	local format = control.format
    	local maximum = control.maximum
    	local lastauthoramp = control.lastauthoramp;
    	local text = {}
    
    	if 'vanc' == format then													-- Vancouver-like author/editor name styling?
    		sep = ',';																-- name-list separator between authors is a comma
    		namesep = ' ';															-- last/first separator is a space
    	else
    		sep = ';'																-- name-list separator between authors is a semicolon
    		namesep = ', '															-- last/first separator is <comma><space>
    	end
    	
    	if sep:sub(-1,-1) ~= " " then sep = sep .. " " end
    	if is_set (maximum) and maximum < 1 then return "", 0; end					-- returned 0 is for EditorCount; not used for authors
    	
    	for i,person in ipairs(people) do
    		if is_set(person.last) then
    			local mask = person.mask
    			local one
    			local sep_one = sep;
    			if is_set (maximum) and i > maximum then
    				etal = true;
    				break;
    			elseif (mask ~= nil) then
    				local n = tonumber(mask)
    				if (n ~= nil) then
    					one = string.rep("&mdash;",n)
    				else
    					one = mask;
    					sep_one = " ";
    				end
    			else
    				one = person.last
    				local first = person.first
    				if is_set(first) then 
    					if ( "vanc" == format ) then								-- if vancouver format
    						one = one:gsub ('%.', '');								-- remove periods from surnames (http://www.ncbi.nlm.nih.gov/books/NBK7271/box/A35029/)
    						if not person.corporate and is_good_vanc_name (one, first) then					-- and name is all Latin characters; corporate authors not tested
    							first = reduce_to_initials(first)					-- attempt to convert first name(s) to initials
    						end
    					end
    					one = one .. namesep .. first 
    				end
    				if is_set(person.link) and person.link ~= control.page_name then
    					one = "[[" .. person.link .. "|" .. one .. "]]"				-- link author/editor if this page is not the author's/editor's page
    				end
    			end
    			table.insert( text, one )
    			table.insert( text, sep_one )
    		end
    	end
    
    	local count = #text / 2;													-- (number of names + number of separators) divided by 2
    	if count > 0 then 
    		if count > 1 and is_set(lastauthoramp) and not etal then
    			text[#text-2] = " & ";												-- replace last separator with ampersand text
    		end
    		text[#text] = nil;														-- erase the last separator
    	end
    	
    	local result = table.concat(text)											-- construct list
    	if etal and is_set (result) then											-- etal may be set by |display-authors=etal but we might not have a last-first list
    		result = result .. sep .. ' ' .. cfg.messages['et al'];					-- we've go a last-first list and etal so add et al.
    	end
    	
    	return result, count
    end
    
    --[[--------------------------< A N C H O R _ I D >------------------------------------------------------------
    
    Generates a CITEREF anchor ID if we have at least one name or a date.  Otherwise returns an empty string.
    
    namelist is one of the contributor-, author-, or editor-name lists chosen in that order.  year is Year or anchor_year.
    
    ]]
    local function anchor_id (namelist, year)
    	local names={};																-- a table for the one to four names and year
    	for i,v in ipairs (namelist) do												-- loop through the list and take up to the first four last names
    		names[i] = v.last 
    		if i == 4 then break end												-- if four then done
    	end
    	table.insert (names, year);													-- add the year at the end
    	local id = table.concat(names);												-- concatenate names and year for CITEREF id
    	if is_set (id) then															-- if concatenation is not an empty string
    		return "CITEREF" .. id;													-- add the CITEREF portion
    	else
    		return '';																-- return an empty string; no reason to include CITEREF id in this citation
    	end
    end
    
    
    --[[--------------------------< N A M E _ H A S _ E T A L >----------------------------------------------------
    
    Evaluates the content of author and editor name parameters for variations on the theme of et al.  If found,
    the et al. is removed, a flag is set to true and the function returns the modified name and the flag.
    
    This function never sets the flag to false but returns it's previous state because it may have been set by
    previous passes through this function or by the parameters |display-authors=etal or |display-editors=etal
    
    ]]
    
    local function name_has_etal (name, etal, nocat)
    
    	if is_set (name) then														-- name can be nil in which case just return
    		local etal_pattern = "[;,]? *[\"']*%f[%a][Ee][Tt] *[Aa][Ll][%.\"']*$"	-- variations on the 'et al' theme
    		local others_pattern = "[;,]? *%f[%a]and [Oo]thers";					-- and alternate to et al.
    		
    		if name:match (etal_pattern) then										-- variants on et al.
    			name = name:gsub (etal_pattern, '');								-- if found, remove
    			etal = true;														-- set flag (may have been set previously here or by |display-authors=etal)
    			if not nocat then													-- no categorization for |vauthors=
    				add_maint_cat ('etal');											-- and add a category if not already added
    			end
    		elseif name:match (others_pattern) then									-- if not 'et al.', then 'and others'?
    			name = name:gsub (others_pattern, '');								-- if found, remove
    			etal = true;														-- set flag (may have been set previously here or by |display-authors=etal)
    			if not nocat then													-- no categorization for |vauthors=
    				add_maint_cat ('etal');											-- and add a category if not already added
    			end
    		end
    	end
    	return name, etal;															-- 
    end
    
    --[[--------------------------< E X T R A C T _ N A M E S >----------------------------------------------------
    Gets name list from the input arguments
    
    Searches through args in sequential order to find |lastn= and |firstn= parameters (or their aliases), and their matching link and mask parameters.
    Stops searching when both |lastn= and |firstn= are not found in args after two sequential attempts: found |last1=, |last2=, and |last3= but doesn't
    find |last4= and |last5= then the search is done.
    
    This function emits an error message when there is a |firstn= without a matching |lastn=.  When there are 'holes' in the list of last names, |last1= and |last3=
    are present but |last2= is missing, an error message is emitted. |lastn= is not required to have a matching |firstn=.
    
    When an author or editor parameter contains some form of 'et al.', the 'et al.' is stripped from the parameter and a flag (etal) returned
    that will cause list_people() to add the static 'et al.' text from Module:Citation/CS1/Configuration.  This keeps 'et al.' out of the 
    template's metadata.  When this occurs, the page is added to a maintenance category.
    
    ]]
    
    local function extract_names(args, list_name)
    	local names = {};			-- table of names
    	local last;					-- individual name components
    	local first;
    	local link;
    	local mask;
    	local i = 1;				-- loop counter/indexer
    	local n = 1;				-- output table indexer
    	local count = 0;			-- used to count the number of times we haven't found a |last= (or alias for authors, |editor-last or alias for editors)
    	local etal=false;			-- return value set to true when we find some form of et al. in an author parameter
    
    	local err_msg_list_name = list_name:match ("(%w+)List") .. 's list';		-- modify AuthorList or EditorList for use in error messages if necessary
    	while true do
    		last = select_one( args, cfg.aliases[list_name .. '-Last'], 'redundant_parameters', i );		-- search through args for name components beginning at 1
    		first = select_one( args, cfg.aliases[list_name .. '-First'], 'redundant_parameters', i );
    		link = select_one( args, cfg.aliases[list_name .. '-Link'], 'redundant_parameters', i );
    		mask = select_one( args, cfg.aliases[list_name .. '-Mask'], 'redundant_parameters', i );
    
    		last, etal = name_has_etal (last, etal, false);								-- find and remove variations on et al.
    		first, etal = name_has_etal (first, etal, false);								-- find and remove variations on et al.
    
    		if first and not last then												-- if there is a firstn without a matching lastn
    			table.insert( z.message_tail, { set_error( 'first_missing_last', {err_msg_list_name, i}, true ) } );	-- add this error message
    		elseif not first and not last then										-- if both firstn and lastn aren't found, are we done?
    			count = count + 1;													-- number of times we haven't found last and first
    			if 2 <= count then													-- two missing names and we give up
    				break;															-- normal exit or there is a two-name hole in the list; can't tell which
    			end
    		else																	-- we have last with or without a first
    			if is_set (link) and false == link_param_ok (link) then				-- do this test here in case link is missing last
    				table.insert( z.message_tail, { set_error( 'bad_paramlink', list_name:match ("(%w+)List"):lower() .. '-link' .. i )});			-- url or wikilink in author link;
    			end
    			names[n] = {last = last, first = first, link = link, mask = mask, corporate=false};	-- add this name to our names list (corporate for |vauthors= only)
    			n = n + 1;															-- point to next location in the names table
    			if 1 == count then													-- if the previous name was missing
    				table.insert( z.message_tail, { set_error( 'missing_name', {err_msg_list_name, i-1}, true ) } );		-- add this error message
    			end
    			count = 0;															-- reset the counter, we're looking for two consecutive missing names
    		end
    		i = i + 1;																-- point to next args location
    	end
    	
    	return names, etal;															-- all done, return our list of names
    end
    
    --[[--------------------------< B U I L D _ I D _ L I S T >--------------------------------------------------------
    
    Populates ID table from arguments using configuration settings. Loops through cfg.id_handlers and searches args for
    any of the parameters listed in each cfg.id_handlers['...'].parameters.  If found, adds the parameter and value to
    the identifier list.  Emits redundant error message is more than one alias exists in args
    
    ]]
    
    local function extract_ids( args )
    	local id_list = {};															-- list of identifiers found in args
    	for k, v in pairs( cfg.id_handlers ) do										-- k is uc identifier name as index to cfg.id_handlers; e.g. cfg.id_handlers['ISBN'], v is a table
    		v = select_one( args, v.parameters, 'redundant_parameters' );			-- v.parameters is a table of aliases for k; here we pick one from args if present
    		if is_set(v) then id_list[k] = v; end									-- if found in args, add identifier to our list
    	end
    	return id_list;
    end
    
    --[[--------------------------< B U I L D _ I D _ L I S T >--------------------------------------------------------
    
    Takes a table of IDs created by extract_ids() and turns it into a table of formatted ID outputs.
    
    inputs:
    	id_list – table of identifiers built by extract_ids()
    	options – table of various template parameter values used to modify some manually handled identifiers
    
    ]]
    
    local function build_id_list( id_list, options )
    	local new_list, handler = {};
    
    	function fallback(k) return { __index = function(t,i) return cfg.id_handlers[k][i] end } end;
    	
    	for k, v in pairs( id_list ) do												-- k is uc identifier name as index to cfg.id_handlers; e.g. cfg.id_handlers['ISBN'], v is a table
    		-- fallback to read-only cfg
    		handler = setmetatable( { ['id'] = v }, fallback(k) );
    		
    		if handler.mode == 'external' then
    			table.insert( new_list, {handler.label, external_link_id( handler ) } );
    		elseif handler.mode == 'internal' then
    			table.insert( new_list, {handler.label, internal_link_id( handler ) } );
    		elseif handler.mode ~= 'manual' then
    			error( cfg.messages['unknown_ID_mode'] );
    		elseif k == 'DOI' then
    			table.insert( new_list, {handler.label, doi( v, options.DoiBroken ) } );
    		elseif k == 'ARXIV' then
    			table.insert( new_list, {handler.label, arxiv( v, options.Class ) } ); 
    		elseif k == 'ASIN' then
    			table.insert( new_list, {handler.label, amazon( v, options.ASINTLD ) } ); 
    		elseif k == 'LCCN' then
    			table.insert( new_list, {handler.label, lccn( v ) } );
    		elseif k == 'OL' or k == 'OLA' then
    			table.insert( new_list, {handler.label, openlibrary( v ) } );
    		elseif k == 'PMC' then
    			table.insert( new_list, {handler.label, pmc( v, options.Embargo ) } );
    		elseif k == 'PMID' then
    			table.insert( new_list, {handler.label, pmid( v ) } );
    		elseif k == 'ISMN' then
    			table.insert( new_list, {handler.label, ismn( v ) } );
    		elseif k == 'ISSN' then
    			table.insert( new_list, {handler.label, issn( v ) } );
    		elseif k == 'ISBN' then
    			local ISBN = internal_link_id( handler );
    			if not check_isbn( v ) and not is_set(options.IgnoreISBN) then
    				ISBN = ISBN .. set_error( 'bad_isbn', {}, false, " ", "" );
    			end
    			table.insert( new_list, {handler.label, ISBN } );				
    		elseif k == 'USENETID' then
    			table.insert( new_list, {handler.label, message_id( v ) } );
    		else
    			error( cfg.messages['unknown_manual_ID'] );
    		end
    	end
    	
    	function comp( a, b )	-- used in following table.sort()
    		return a[1] < b[1];
    	end
    	
    	table.sort( new_list, comp );
    	for k, v in ipairs( new_list ) do
    		new_list[k] = v[2];
    	end
    	
    	return new_list;
    end
      
    
    --[[--------------------------< C O I N S _ C L E A N U P >----------------------------------------------------
    
    Cleanup parameter values for the metadata by removing or replacing invisible characters and certain html entities.
    
    2015-12-10: there is a bug in mw.text.unstripNoWiki ().  It replaced math stripmarkers with the appropriate content
    when it shouldn't.  See https://phabricator.wikimedia.org/T121085 and Wikipedia_talk:Lua#stripmarkers_and_mw.text.unstripNoWiki.28.29
    
    TODO: move the replacement patterns and replacement values into a table in /Configuration similar to the invisible
    characters table?
    ]]
    
    local function coins_cleanup (value)
    	value = mw.text.unstripNoWiki (value);										-- replace nowiki stripmarkers with their content
    	value = value:gsub ('<span class="nowrap" style="padding%-left:0%.1em;">&#39;s</span>', "'s");	-- replace {{'s}} template with simple apostrophe-s
    	value = value:gsub ('&zwj;\226\128\138\039\226\128\139', "'");				-- replace {{'}} with simple apostrophe
    	value = value:gsub ('\226\128\138\039\226\128\139', "'");					-- replace {{'}} with simple apostrophe (as of 2015-12-11)
    	value = value:gsub ('&nbsp;', ' ');											-- replace &nbsp; entity with plain space
    	value = value:gsub ('\226\128\138', ' ');									-- replace hair space with plain space
    	value = value:gsub ('&zwj;', '');											-- remove &zwj; entities
    	value = value:gsub ('[\226\128\141\226\128\139]', '')						-- remove zero-width joiner, zero-width space
    	value = value:gsub ('[\194\173\009\010\013]', ' ');							-- replace soft hyphen, horizontal tab, line feed, carriage return with plain space
    	return value;
    end
    
    
    --[[--------------------------< C O I N S >--------------------------------------------------------------------
    
    COinS metadata (see <http://ocoins.info/>) allows automated tools to parse the citation information.
    
    ]]
    
    local function COinS(data, class)
    	if 'table' ~= type(data) or nil == next(data) then
    		return '';
    	end
    
    	for k, v in pairs (data) do													-- spin through all of the metadata parameter values
    		if 'ID_list' ~= k and 'Authors' ~= k then								-- except the ID_list and Author tables (author nowiki stripmarker done when Author table processed)
    			data[k] = coins_cleanup (v);
    		end
    	end
    
    	local ctx_ver = "Z39.88-2004";
    	
    	-- treat table strictly as an array with only set values.
    	local OCinSoutput = setmetatable( {}, {
    		__newindex = function(self, key, value)
    			if is_set(value) then
    				rawset( self, #self+1, table.concat{ key, '=', mw.uri.encode( remove_wiki_link( value ) ) } );
    			end
    		end
    	});
    	
    	if in_array (class, {'arxiv', 'journal', 'news'}) or (in_array (class, {'conference', 'interview', 'map', 'press release', 'web'}) and is_set(data.Periodical)) or 
    		('citation' == class and is_set(data.Periodical) and not is_set (data.Encyclopedia)) then
    			OCinSoutput.rft_val_fmt = "info:ofi/fmt:kev:mtx:journal";			-- journal metadata identifier
    			if 'arxiv' == class then											-- set genre according to the type of citation template we are rendering
    				OCinSoutput["rft.genre"] = "preprint";							-- cite arxiv
    			elseif 'conference' == class then
    				OCinSoutput["rft.genre"] = "conference";						-- cite conference (when Periodical set)
    			elseif 'web' == class then
    				OCinSoutput["rft.genre"] = "unknown";							-- cite web (when Periodical set)
    			else
    				OCinSoutput["rft.genre"] = "article";							-- journal and other 'periodical' articles
    			end
    			OCinSoutput["rft.jtitle"] = data.Periodical;						-- journal only
    			if is_set (data.Map) then
    				OCinSoutput["rft.atitle"] = data.Map;							-- for a map in a periodical
    			else
    				OCinSoutput["rft.atitle"] = data.Title;							-- all other 'periodical' article titles
    			end
    																				-- these used onlu for periodicals
    			OCinSoutput["rft.ssn"] = data.Season;								-- keywords: winter, spring, summer, fall
    			OCinSoutput["rft.chron"] = data.Chron;								-- free-form date components
    			OCinSoutput["rft.volume"] = data.Volume;							-- does not apply to books
    			OCinSoutput["rft.issue"] = data.Issue;
    			OCinSoutput["rft.pages"] = data.Pages;								-- also used in book metadata
    
    	elseif 'thesis' ~= class then												-- all others except cite thesis are treated as 'book' metadata; genre distinguishes
    		OCinSoutput.rft_val_fmt = "info:ofi/fmt:kev:mtx:book";					-- book metadata identifier
    		if 'report' == class or 'techreport' == class then						-- cite report and cite techreport
    			OCinSoutput["rft.genre"] = "report";
    		elseif 'conference' == class then										-- cite conference when Periodical not set
    			OCinSoutput["rft.genre"] = "conference";
    		elseif in_array (class, {'book', 'citation', 'encyclopaedia', 'interview', 'map'}) then
    			if is_set (data.Chapter) then
    				OCinSoutput["rft.genre"] = "bookitem";
    				OCinSoutput["rft.atitle"] = data.Chapter;						-- book chapter, encyclopedia article, interview in a book, or map title
    			else
    				if 'map' == class or 'interview' == class then
    					OCinSoutput["rft.genre"] = 'unknown';						-- standalone map or interview
    				else
    					OCinSoutput["rft.genre"] = 'book';							-- book and encyclopedia
    				end
    			end
    		else	--{'audio-visual', 'AV-media-notes', 'DVD-notes', 'episode', 'interview', 'mailinglist', 'map', 'newsgroup', 'podcast', 'press release', 'serial', 'sign', 'speech', 'web'}
    			OCinSoutput["rft.genre"] = "unknown";
    		end
    		OCinSoutput["rft.btitle"] = data.Title;									-- book only
    		OCinSoutput["rft.place"] = data.PublicationPlace;						-- book only
    		OCinSoutput["rft.series"] = data.Series;								-- book only
    		OCinSoutput["rft.pages"] = data.Pages;									-- book, journal
    		OCinSoutput["rft.edition"] = data.Edition;								-- book only
    		OCinSoutput["rft.pub"] = data.PublisherName;							-- book and dissertation
    		
    	else																		-- cite thesis
    		OCinSoutput.rft_val_fmt = "info:ofi/fmt:kev:mtx:dissertation";			-- dissertation metadata identifier
    		OCinSoutput["rft.title"] = data.Title;									-- dissertation (also patent but that is not yet supported)
    		OCinSoutput["rft.degree"] = data.Degree;								-- dissertation only
    		OCinSoutput['rft.inst'] = data.PublisherName;							-- book and dissertation
    	end
    																				-- and now common parameters (as much as possible)
    	OCinSoutput["rft.date"] = data.Date;										-- book, journal, dissertation
    	
    	for k, v in pairs( data.ID_list ) do										-- what to do about these? For now assume that they are common to all?
    		if k == 'ISBN' then v = clean_isbn( v ) end
    		local id = cfg.id_handlers[k].COinS;
    		if string.sub( id or "", 1, 4 ) == 'info' then							-- for ids that are in the info:registry
    			OCinSoutput["rft_id"] = table.concat{ id, "/", v };
    		elseif string.sub (id or "", 1, 3 ) == 'rft' then						-- for isbn, issn, eissn, etc that have defined COinS keywords
    			OCinSoutput[ id ] = v;
    		elseif id then															-- when cfg.id_handlers[k].COinS is not nil
    			OCinSoutput["rft_id"] = table.concat{ cfg.id_handlers[k].prefix, v };	-- others; provide a url
    		end
    	end
    
    --[[	
    	for k, v in pairs( data.ID_list ) do										-- what to do about these? For now assume that they are common to all?
    		local id, value = cfg.id_handlers[k].COinS;
    		if k == 'ISBN' then value = clean_isbn( v ); else value = v; end
    		if string.sub( id or "", 1, 4 ) == 'info' then
    			OCinSoutput["rft_id"] = table.concat{ id, "/", v };
    		else
    			OCinSoutput[ id ] = value;
    		end
    	end
    ]]
    	local last, first;
    	for k, v in ipairs( data.Authors ) do
    		last, first = coins_cleanup (v.last), coins_cleanup (v.first or '');	-- replace any nowiki strip markers, non-printing or invisible characers
    		if k == 1 then															-- for the first author name only
    			if is_set(last)  and is_set(first) then								-- set these COinS values if |first= and |last= specify the first author name
    				OCinSoutput["rft.aulast"] = last;								-- book, journal, dissertation
    				OCinSoutput["rft.aufirst"] = first;								-- book, journal, dissertation
    			elseif is_set(last) then 
    				OCinSoutput["rft.au"] = last;									-- book, journal, dissertation -- otherwise use this form for the first name
    			end
    		else																	-- for all other authors
    			if is_set(last) and is_set(first) then
    				OCinSoutput["rft.au"] = table.concat{ last, ", ", first };		-- book, journal, dissertation
    			elseif is_set(last) then
    				OCinSoutput["rft.au"] = last;									-- book, journal, dissertation
    			end
    		end
    	end
    
    	OCinSoutput.rft_id = data.URL;
    	OCinSoutput.rfr_id = table.concat{ "info:sid/", mw.site.server:match( "[^/]*$" ), ":", data.RawPage };
    	OCinSoutput = setmetatable( OCinSoutput, nil );
    	
    	-- sort with version string always first, and combine.
    	table.sort( OCinSoutput );
    	table.insert( OCinSoutput, 1, "ctx_ver=" .. ctx_ver );  -- such as "Z39.88-2004"
    	return table.concat(OCinSoutput, "&");
    end
    
    
    --[[--------------------------< G E T _ I S O 6 3 9 _ C O D E >------------------------------------------------
    
    Validates language names provided in |language= parameter if not an ISO639-1 code.  Handles the special case that is Norwegian where
    ISO639-1 code 'no' is mapped to language name 'Norwegian Bokmål' by Extention:CLDR.
    
    Returns the language name and associated ISO639-1 code.  Because case of the source may be incorrect or different from the case that Wikimedia
    uses, the name comparisons are done in lower case and when a match is found, the Wikimedia version (assumed to be correct) is returned along
    with the code.  When there is no match, we return the original language name string.
    
    mw.language.fetchLanguageNames() will return a list of languages that aren't part of ISO639-1. Names that aren't ISO639-1 but that are included
    in the list will be found if that name is provided in the |language= parameter.  For example, if |language=Samaritan Aramaic, that name will be
    found with the associated code 'sam', not an ISO639-1 code.  When names are found and the associated code is not two characters, this function
    returns only the Wikimedia language name.
    
    Adapted from code taken from Module:Check ISO 639-1.
    
    ]]
    
    local function get_iso639_code (lang)
    	if 'norwegian' == lang:lower() then											-- special case related to Wikimedia remap of code 'no' at Extension:CLDR
    		return 'Norwegian', 'no';												-- Make sure rendered version is properly capitalized
    	end
    	
    	local languages = mw.language.fetchLanguageNames('en', 'all')				-- get a list of language names known to Wikimedia
    																				-- ('all' is required for North Ndebele, South Ndebele, and Ojibwa)
    	local langlc = mw.ustring.lower(lang);										-- lower case version for comparisons
    	
    	for code, name in pairs(languages) do										-- scan the list to see if we can find our language
    		if langlc == mw.ustring.lower(name) then
    			if 2 ~= code:len() then												-- ISO639-1 codes only
    				return name;													-- so return the name but not the code
    			end
    			return name, code;													-- found it, return name to ensure proper capitalization and the ISO639-1 code
    		end
    	end
    	return lang;																-- not valid language; return language in original case and nil for ISO639-1 code
    end
    
    --[[--------------------------< L A N G U A G E _ P A R A M E T E R >------------------------------------------
    
    Get language name from ISO639-1 code value provided.  If a code is valid use the returned name; if not, then use the value that was provided with the language parameter.
    
    There is an exception.  There are three ISO639-1 codes for Norewegian language variants.  There are two official variants: Norwegian Bokmål (code 'nb') and
    Norwegian Nynorsk (code 'nn').  The third, code 'no',  is defined by ISO639-1 as 'Norwegian' though in Norway this is pretty much meaningless.  However, it appears
    that on enwiki, editors are for the most part unaware of the nb and nn variants (compare page counts for these variants at Category:Articles with non-English-language external links.
    
    Because Norwegian Bokmål is the most common language variant, Media wiki has been modified to return Norwegian Bokmål for ISO639-1 code 'no'. Here we undo that and
    return 'Norwegian' when editors use |language=no.  We presume that editors don't know about the variants or can't descriminate between them.
    
    See Help talk:Citation Style_1#An ISO 639-1 language name test
    
    When |language= contains a valid ISO639-1 code, the page is assigned to the category for that code: Category:Norwegian-language sources (no) if
    the page is a mainspace page and the ISO639-1 code is not 'en'.  Similarly, if the  parameter is |language=Norwegian, it will be categorized in the same way.
    
    This function supports multiple languages in the form |language=nb, French, th where the language names or codes are separated from each other by commas.
    
    ]]
    
    local function language_parameter (lang)
    	local code;																	-- the ISO639-1 two character code
    	local name;																	-- the language name
    	local language_list = {};													-- table of language names to be rendered
    	local names_table = {};														-- table made from the value assigned to |language=
    
    	names_table = mw.text.split (lang, '%s*,%s*');								-- names should be a comma separated list
    
    	for _, lang in ipairs (names_table) do										-- reuse lang
    
    		if lang:match ('^%a%a%-') then											-- strip ietf language tags from code
    			lang = lang:match ('(%a%a)%-')										-- keep only 639-1 code portion to lang; TODO: do something with 3166 alpha 2 country code?
    		end
    		if 2 == lang:len() then													-- ISO639-1 language code are 2 characters (fetchLanguageName also supports 3 character codes)
    			name = mw.language.fetchLanguageName( lang:lower(), "en" );			-- get ISO 639-1 language name if Language is a proper code
    		end
    	
    		if is_set (name) then													-- if Language specified a valid ISO639-1 code
    			code = lang:lower();												-- save it
    		else
    			name, code = get_iso639_code (lang);								-- attempt to get code from name (assign name here so that we are sure of proper capitalization)
    		end
    	
    		if is_set (code) then
    			if 'no' == code then name = 'Norwegian' end;						-- override wikimedia when code is 'no'
    			if 'en' ~= code then												-- English not the language
    				add_prop_cat ('foreign_lang_source', {name, code})
    			end
    		else
    			add_maint_cat ('unknown_lang');										-- add maint category if not already added
    		end
    		
    		table.insert (language_list, name);
    		name = '';																-- so we can reuse it
    	end
    	
    	code = #language_list														-- reuse code as number of languages in the list
    	if 2 >= code then
    		name = table.concat (language_list, ' and ')							-- insert '<space>and<space>' between two language names
    	elseif 2 < code then
    		language_list[code] = 'and ' .. language_list[code];					-- prepend last name with 'and<space>'
    		name = table.concat (language_list, ', ')								-- and concatenate with '<comma><space>' separators
    	end
    	if 'English' == name then
    		return '';																-- if one language and that language is English return an empty string (no annotation)
    	end
    	return (" " .. wrap_msg ('language', name));								-- otherwise wrap with '(in ...)'
    end
    
    --[[--------------------------< S E T _ C S 1 _ S T Y L E >----------------------------------------------------
    
    Set style settings for CS1 citation templates. Returns separator and postscript settings
    
    ]]
    
    local function set_cs1_style (ps)
    	if not is_set (ps) then														-- unless explicitely set to something
    		ps = '.';																-- terminate the rendered citation with a period
    	end
    	return '.', ps;																-- separator is a full stop
    end
    
    --[[--------------------------< S E T _ C S 2 _ S T Y L E >----------------------------------------------------
    
    Set style settings for CS2 citation templates. Returns separator, postscript, ref settings
    
    ]]
    
    local function set_cs2_style (ps, ref)
    	if not is_set (ps) then														-- if |postscript= has not been set, set cs2 default
    		ps = '';																-- make sure it isn't nil
    	end
    	if not is_set (ref) then													-- if |ref= is not set
    		ref = "harv";															-- set default |ref=harv
    	end
    	return ',', ps, ref;														-- separator is a comma
    end
    
    --[[--------------------------< G E T _ S E T T I N G S _ F R O M _ C I T E _ C L A S S >----------------------
    
    When |mode= is not set or when its value is invalid, use config.CitationClass and parameter values to establish
    rendered style.
    
    ]]
    
    local function get_settings_from_cite_class (ps, ref, cite_class)
    	local sep;
    	if (cite_class == "citation") then											-- for citation templates (CS2)
    		sep, ps, ref = set_cs2_style (ps, ref);
    	else																		-- not a citation template so CS1
    		sep, ps = set_cs1_style (ps);
    	end
    
    	return sep, ps, ref															-- return them all
    end
    
    --[[--------------------------< S E T _ S T Y L E >------------------------------------------------------------
    
    Establish basic style settings to be used when rendering the citation.  Uses |mode= if set and valid or uses
    config.CitationClass from the template's #invoke: to establish style.
    
    ]]
    
    local function set_style (mode, ps, ref, cite_class)
    	local sep;
    	if 'cs2' == mode then														-- if this template is to be rendered in CS2 (citation) style
    		sep, ps, ref = set_cs2_style (ps, ref);
    	elseif 'cs1' == mode then													-- if this template is to be rendered in CS1 (cite xxx) style
    		sep, ps = set_cs1_style (ps);
    	else																		-- anything but cs1 or cs2
    		sep, ps, ref = get_settings_from_cite_class (ps, ref, cite_class);		-- get settings based on the template's CitationClass
    	end
    	if 'none' == ps:lower() then												-- if assigned value is 'none' then
    		ps = '';																-- set to empty string
    	end
    	
    	return sep, ps, ref
    end
    
    --[=[-------------------------< I S _ P D F >------------------------------------------------------------------
    
    Determines if a url has the file extension that is one of the pdf file extensions used by [[MediaWiki:Common.css]] when
    applying the pdf icon to external links.
    
    returns true if file extension is one of the recognized extension, else false
    
    ]=]
    
    local function is_pdf (url)
    	return url:match ('%.pdf[%?#]?') or url:match ('%.PDF[%?#]?');
    end
    
    --[[--------------------------< S T Y L E _ F O R M A T >------------------------------------------------------
    
    Applies css style to |format=, |chapter-format=, etc.  Also emits an error message if the format parameter does
    not have a matching url parameter.  If the format parameter is not set and the url contains a file extension that
    is recognized as a pdf document by MediaWiki's commons.css, this code will set the format parameter to (PDF) with
    the appropriate styling.
    
    ]]
    
    local function style_format (format, url, fmt_param, url_param)
    	if is_set (format) then
    		format = wrap_style ('format', format);									-- add leading space, parenthases, resize
    		if not is_set (url) then
    			format = format .. set_error( 'format_missing_url', {fmt_param, url_param} );	-- add an error message
    		end
    	elseif is_pdf (url) then													-- format is not set so if url is a pdf file then
    		format = wrap_style ('format', 'PDF');									-- set format to pdf
    	else
    		format = '';															-- empty string for concatenation
    	end
    	return format;
    end
    
    --[[--------------------------< G E T _ D I S P L A Y _ A U T H O R S _ E D I T O R S >------------------------
    
    Returns a number that may or may not limit the length of the author or editor name lists.
    
    When the value assigned to |display-authors= is a number greater than or equal to zero, return the number and
    the previous state of the 'etal' flag (false by default but may have been set to true if the name list contains
    some variant of the text 'et al.').
    
    When the value assigned to |display-authors= is the keyword 'etal', return a number that is one greater than the
    number of authors in the list and set the 'etal' flag true.  This will cause the list_people() to display all of
    the names in the name list followed by 'et al.'
    
    In all other cases, returns nil and the previous state of the 'etal' flag.
    
    ]]
    
    local function get_display_authors_editors (max, count, list_name, etal)
    	if is_set (max) then
    		if 'etal' == max:lower():gsub("[ '%.]", '') then						-- the :gsub() portion makes 'etal' from a variety of 'et al.' spellings and stylings
    			max = count + 1;													-- number of authors + 1 so display all author name plus et al.
    			etal = true;														-- overrides value set by extract_names()
    		elseif max:match ('^%d+$') then											-- if is a string of numbers
    			max = tonumber (max);												-- make it a number
    			if max >= count and 'authors' == list_name then	-- AUTHORS ONLY		-- if |display-xxxxors= value greater than or equal to number of authors/editors
    				add_maint_cat ('disp_auth_ed', list_name);
    			end
    		else																	-- not a valid keyword or number
    			table.insert( z.message_tail, { set_error( 'invalid_param_val', {'display-' .. list_name, max}, true ) } );		-- add error message
    			max = nil;															-- unset
    		end
    	elseif 'authors' == list_name then		-- AUTHORS ONLY	need to clear implicit et al category
    		max = count + 1;														-- number of authors + 1
    	end
    	
    	return max, etal;
    end
    
    --[[--------------------------< E X T R A _ T E X T _ I N _ P A G E _ C H E C K >------------------------------
    
    Adds page to Category:CS1 maint: extra text if |page= or |pages= has what appears to be some form of p. or pp. 
    abbreviation in the first characters of the parameter content.
    
    check Page and Pages for extraneous p, p., pp, and pp. at start of parameter value:
    	good pattern: '^P[^%.P%l]' matches when |page(s)= begins PX or P# but not Px where x and X are letters and # is a dgiit
    	bad pattern: '^[Pp][Pp]' matches matches when |page(s)= begins pp or pP or Pp or PP
    
    ]]
    
    local function extra_text_in_page_check (page)
    --	local good_pattern = '^P[^%.P%l]';
    	local good_pattern = '^P[^%.Pp]';											-- ok to begin with uppercase P: P7 (pg 7 of section P) but not p123 (page 123) TODO: add Gg for PG or Pg?
    --	local bad_pattern = '^[Pp][Pp]';
    	local bad_pattern = '^[Pp]?[Pp]%.?[ %d]';
    
    	if not page:match (good_pattern) and (page:match (bad_pattern) or  page:match ('^[Pp]ages?')) then
    		add_maint_cat ('extra_text');
    	end
    --		if Page:match ('^[Pp]?[Pp]%.?[ %d]') or  Page:match ('^[Pp]ages?[ %d]') or
    --			Pages:match ('^[Pp]?[Pp]%.?[ %d]') or  Pages:match ('^[Pp]ages?[ %d]') then
    --				add_maint_cat ('extra_text');
    --		end
    end
    
    
    --[[--------------------------< P A R S E _ V A U T H O R S _ V E D I T O R S >--------------------------------
    
    This function extracts author / editor names from |vauthors= or |veditors= and finds matching |xxxxor-maskn= and
    |xxxxor-linkn= in args.  It then returns a table of assembled names just as extract_names() does.
    
    Author / editor names in |vauthors= or |veditors= must be in Vancouver system style. Corporate or institutional names
    may sometimes be required and because such names will often fail the is_good_vanc_name() and other format compliance
    tests, are wrapped in doubled paranethese ((corporate name)) to suppress the format tests.
    
    This function sets the vancouver error when a reqired comma is missing and when there is a space between an author's initials.
    
    ]]
    
    local function parse_vauthors_veditors (args, vparam, list_name)
    	local names = {};															-- table of names assembled from |vauthors=, |author-maskn=, |author-linkn=
    	local v_name_table = {};
    	local etal = false;															-- return value set to true when we find some form of et al. vauthors parameter
    	local last, first, link, mask;
    	local corporate = false;
    
    	vparam, etal = name_has_etal (vparam, etal, true);							-- find and remove variations on et al. do not categorize (do it here because et al. might have a period)
    	if vparam:find ('%[%[') or vparam:find ('%]%]')	then						-- no wikilinking vauthors names
    		add_vanc_error ();
    	end
    	v_name_table = mw.text.split(vparam, "%s*,%s*")								-- names are separated by commas
    
    	for i, v_name in ipairs(v_name_table) do
    		if v_name:match ('^%(%(.+%)%)$') then									-- corporate authors are wrapped in doubled parenthese to supress vanc formatting and error detection
    			first = '';															-- set to empty string for concatenation and because it may have been set for previous author/editor
    			last = v_name:match ('^%(%((.+)%)%)$')
    			corporate = true;
    		elseif string.find(v_name, "%s") then
    		    lastfirstTable = {}
    		    lastfirstTable = mw.text.split(v_name, "%s")
    		    first = table.remove(lastfirstTable);								-- removes and returns value of last element in table which should be author intials
    		    last  = table.concat(lastfirstTable, " ")							-- returns a string that is the concatenation of all other names that are not initials
    		    if mw.ustring.match (last, '%a+%s+%u+%s+%a+') or mw.ustring.match (v_name, ' %u %u$') then
    				add_vanc_error ();												-- matches last II last; the case when a comma is missing or a space between two intiials
    			end
    		else
    			first = '';															-- set to empty string for concatenation and because it may have been set for previous author/editor
    			last = v_name;														-- last name or single corporate name?  Doesn't support multiword corporate names? do we need this?
    		end
    																
    		if is_set (first) and not mw.ustring.match (first, "^%u?%u$") then		-- first shall contain one or two upper-case letters, nothing else
    			add_vanc_error ();
    		end
    																				-- this from extract_names ()
    		link = select_one( args, cfg.aliases[list_name .. '-Link'], 'redundant_parameters', i );
    		mask = select_one( args, cfg.aliases[list_name .. '-Mask'], 'redundant_parameters', i );
    		names[i] = {last = last, first = first, link = link, mask = mask, corporate=corporate};		-- add this assembled name to our names list
    	end
    	return names, etal;															-- all done, return our list of names
    end
    
    --[[--------------------------< S E L E C T _ A U T H O R _ E D I T O R _ S O U R C E >------------------------
    
    Select one of |authors=, |authorn= / |lastn / firstn=, or |vauthors= as the source of the author name list or
    select one of |editors=, |editorn= / editor-lastn= / |editor-firstn= or |veditors= as the source of the editor name list.
    
    Only one of these appropriate three will be used.  The hierarchy is: |authorn= (and aliases) highest and |authors= lowest and
    similarly, |editorn= (and aliases) highest and |editors= lowest
    
    When looking for |authorn= / |editorn= parameters, test |xxxxor1= and |xxxxor2= (and all of their aliases); stops after the second
    test which mimicks the test used in extract_names() when looking for a hole in the author name list.  There may be a better
    way to do this, I just haven't discovered what that way is.
    
    Emits an error message when more than one xxxxor name source is provided.
    
    In this function, vxxxxors = vauthors or veditors; xxxxors = authors or editors as appropriate.
    
    ]]
    
    local function select_author_editor_source (vxxxxors, xxxxors, args, list_name)
    local lastfirst = false;
    	if select_one( args, cfg.aliases[list_name .. '-Last'], 'none', 1 ) or		-- do this twice incase we have a first 1 without a last1
    		select_one( args, cfg.aliases[list_name .. '-Last'], 'none', 2 ) then
    			lastfirst=true;
    	end
    
    	if (is_set (vxxxxors) and true == lastfirst) or								-- these are the three error conditions
    		(is_set (vxxxxors) and is_set (xxxxors)) or
    		(true == lastfirst and is_set (xxxxors)) then
    			local err_name;
    			if 'AuthorList' == list_name then									-- figure out which name should be used in error message
    				err_name = 'author';
    			else
    				err_name = 'editor';
    			end
    			table.insert( z.message_tail, { set_error( 'redundant_parameters',
    				{err_name .. '-name-list parameters'}, true ) } );				-- add error message
    	end
    
    	if true == lastfirst then return 1 end;										-- return a number indicating which author name source to use
    	if is_set (vxxxxors) then return 2 end;
    	if is_set (xxxxors) then return 3 end;
    	return 1;																	-- no authors so return 1; this allows missing author name test to run in case there is a first without last 
    end
    
    
    --[[--------------------------< I S _ V A L I D _ P A R A M E T E R _ V A L U E >------------------------------
    
    This function is used to validate a parameter's assigned value for those parameters that have only a limited number
    of allowable values (yes, y, true, no, etc).  When the parameter value has not been assigned a value (missing or empty
    in the source template) the function refurns true.  If the parameter value is one of the list of allowed values returns
    true; else, emits an error message and returns false.
    
    ]]
    
    local function is_valid_parameter_value (value, name, possible)
    	if not is_set (value) then
    		return true;															-- an empty parameter is ok
    	elseif in_array(value:lower(), possible) then
    		return true;
    	else
    		table.insert( z.message_tail, { set_error( 'invalid_param_val', {name, value}, true ) } );	-- not an allowed value so add error message
    		return false
    	end
    end
    
    
    --[[--------------------------< T E R M I N A T E _ N A M E _ L I S T >----------------------------------------
    
    This function terminates a name list (author, contributor, editor) with a separator character (sepc) and a space
    when the last character is not a sepc character or when the last three characters are not sepc followed by two
    closing square brackets (close of a wikilink).  When either of these is true, the name_list is terminated with a
    single space character.
    
    ]]
    
    local function terminate_name_list (name_list, sepc)
    	if (string.sub (name_list,-1,-1) == sepc) or (string.sub (name_list,-3,-1) == sepc .. ']]') then	-- if last name in list ends with sepc char
    		return name_list .. " ";												-- don't add another
    	else
    		return name_list .. sepc .. ' ';										-- otherwise terninate the name list
    	end
    end
    
    
    --[[-------------------------< F O R M A T _ V O L U M E _ I S S U E >----------------------------------------
    
    returns the concatenation of the formatted volume and issue parameters as a single string; or formatted volume
    or formatted issue, or an empty string if neither are set.
    
    ]]
    	
    local function format_volume_issue (volume, issue, cite_class, origin, sepc, lower)
    	if not is_set (volume) and not is_set (issue) then
    		return '';
    	end
    	
    	if 'magazine' == cite_class or (in_array (cite_class, {'citation', 'map'}) and 'magazine' == origin) then
    		if is_set (volume) and is_set (issue) then
    			return wrap_msg ('vol-no', {sepc, volume, issue}, lower);
    		elseif is_set (volume) then
    			return wrap_msg ('vol', {sepc, volume}, lower);
    		else
    			return wrap_msg ('issue', {sepc, issue}, lower);
    		end
    	end
    	
    	local vol = '';
    		
    	if is_set (volume) then
    		if (4 < mw.ustring.len(volume)) then
    			vol = substitute (cfg.messages['j-vol'], {sepc, volume});
    		else
    			vol = wrap_style ('vol-bold', hyphen_to_dash(volume));
    		end
    	end
    	if is_set (issue) then
    		return vol .. substitute (cfg.messages['j-issue'], issue);
    	end
    	return vol;
    end
    
    
    --[[-------------------------< F O R M A T _ P A G E S _ S H E E T S >-----------------------------------------
    
    adds static text to one of |page(s)= or |sheet(s)= values and returns it with all of the others set to empty strings.
    The return order is:
    	page, pages, sheet, sheets
    
    Singular has priority over plural when both are provided.
    
    ]]
    
    local function format_pages_sheets (page, pages, sheet, sheets, cite_class, origin, sepc, nopp, lower)
    	if 'map' == cite_class then													-- only cite map supports sheet(s) as in-source locators
    		if is_set (sheet) then
    			if 'journal' == origin then
    				return '', '', wrap_msg ('j-sheet', sheet, lower), '';
    			else
    				return '', '', wrap_msg ('sheet', {sepc, sheet}, lower), '';
    			end
    		elseif is_set (sheets) then
    			if 'journal' == origin then
    				return '', '', '', wrap_msg ('j-sheets', sheets, lower);
    			else
    				return '', '', '', wrap_msg ('sheets', {sepc, sheets}, lower);
    			end
    		end
    	end
    
    	local is_journal = 'journal' == cite_class or (in_array (cite_class, {'citation', 'map'}) and 'journal' == origin);
    
    	if is_set (page) then
    		if is_journal then
    			return substitute (cfg.messages['j-page(s)'], page), '', '', '';
    		elseif not nopp then
    			return substitute (cfg.messages['p-prefix'], {sepc, page}), '', '', '';
    		else
    			return substitute (cfg.messages['nopp'], {sepc, page}), '', '', '';
    		end
    	elseif is_set(pages) then
    		if is_journal then
    			return substitute (cfg.messages['j-page(s)'], pages), '', '', '';
    		elseif tonumber(pages) ~= nil and not nopp then										-- if pages is only digits, assume a single page number
    			return '', substitute (cfg.messages['p-prefix'], {sepc, pages}), '', '';
    		elseif not nopp then
    			return '', substitute (cfg.messages['pp-prefix'], {sepc, pages}), '', '';
    		else
    			return '', substitute (cfg.messages['nopp'], {sepc, pages}), '', '';
    		end
    	end
    	
    	return '', '', '', '';														-- return empty strings
    end
    
    --[[--------------------------< C I T A T I O N 0 >------------------------------------------------------------
    
    This is the main function doing the majority of the citation formatting.
    
    ]]
    
    local function citation0( config, args)
    	--[[ 
    	Load Input Parameters
    	The argument_wrapper facilitates the mapping of multiple aliases to single internal variable.
    	]]
    	local A = argument_wrapper( args );
    	local i 
    
    	-- Pick out the relevant fields from the arguments.  Different citation templates
    	-- define different field names for the same underlying things.	
    	local author_etal;
    	local a	= {};																-- authors list from |lastn= / |firstn= pairs or |vauthors=
    	local Authors;
    	local NameListFormat = A['NameListFormat'];
    
    	do																			-- to limit scope of selected
    		local selected = select_author_editor_source (A['Vauthors'], A['Authors'], args, 'AuthorList');
    		if 1 == selected then
    			a, author_etal = extract_names (args, 'AuthorList');				-- fetch author list from |authorn= / |lastn= / |firstn=, |author-linkn=, and |author-maskn=
    		elseif 2 == selected then
    			NameListFormat = 'vanc';											-- override whatever |name-list-format= might be
    			a, author_etal = parse_vauthors_veditors (args, args.vauthors, 'AuthorList');	-- fetch author list from |vauthors=, |author-linkn=, and |author-maskn=
    		elseif 3 == selected then
    			Authors = A['Authors'];												-- use content of |authors=
    		end
    	end
    
    	local Coauthors = A['Coauthors'];
    	local Others = A['Others'];
    
    	local editor_etal;
    	local e	= {};																-- editors list from |editor-lastn= / |editor-firstn= pairs or |veditors=
    	local Editors;
    
    	do																			-- to limit scope of selected
    		local selected = select_author_editor_source (A['Veditors'], A['Editors'], args, 'EditorList');
    		if 1 == selected then
    			e, editor_etal = extract_names (args, 'EditorList');				-- fetch editor list from |editorn= / |editor-lastn= / |editor-firstn=, |editor-linkn=, and |editor-maskn=
    		elseif 2 == selected then
    			NameListFormat = 'vanc';											-- override whatever |name-list-format= might be
    			e, editor_etal = parse_vauthors_veditors (args, args.veditors, 'EditorList');	-- fetch editor list from |veditors=, |editor-linkn=, and |editor-maskn=
    		elseif 3 == selected then
    			Editors = A['Editors'];												-- use content of |editors=
    		end
    	end
    
    	local t = {};																-- translators list from |translator-lastn= / translator-firstn= pairs
    	local Translators;															-- assembled translators name list
    	t = extract_names (args, 'TranslatorList');									-- fetch translator list from |translatorn= / |translator-lastn=, -firstn=, -linkn=, -maskn=
    	
    	local c = {};																-- contributors list from |contributor-lastn= / contributor-firstn= pairs
    	local Contributors;															-- assembled contributors name list
    	local Contribution = A['Contribution'];
    	if in_array(config.CitationClass, {"book","citation"}) and not is_set(A['Periodical']) then	-- |contributor= and |contribution= only supported in book cites
    		c = extract_names (args, 'ContributorList');							-- fetch contributor list from |contributorn= / |contributor-lastn=, -firstn=, -linkn=, -maskn=
    		
    		if 0 < #c then
    			if not is_set (Contribution) then									-- |contributor= requires |contribution=
    				table.insert( z.message_tail, { set_error( 'contributor_missing_required_param', 'contribution')});	-- add missing contribution error message
    				c = {};															-- blank the contributors' table; it is used as a flag later
    			end
    			if 0 == #a then														-- |contributor= requires |author=
    				table.insert( z.message_tail, { set_error( 'contributor_missing_required_param', 'author')});	-- add missing author error message
    				c = {};															-- blank the contributors' table; it is used as a flag later
    			end
    		end
    	else																		-- if not a book cite
    		if select_one (args, cfg.aliases['ContributorList-Last'], 'redundant_parameters', 1 ) then	-- are there contributor name list parameters?
    			table.insert( z.message_tail, { set_error( 'contributor_ignored')});	-- add contributor ignored error message
    		end
    		Contribution = nil;														-- unset
    	end
    
    	if not is_valid_parameter_value (NameListFormat, 'name-list-format', cfg.keywords['name-list-format']) then			-- only accepted value for this parameter is 'vanc'
    		NameListFormat = '';													-- anything else, set to empty string
    	end
    
    	local Year = A['Year'];
    	local PublicationDate = A['PublicationDate'];
    	local OrigYear = A['OrigYear'];
    	local Date = A['Date'];
    	local LayDate = A['LayDate'];
    	------------------------------------------------- Get title data
    	local Title = A['Title'];
    	local ScriptTitle = A['ScriptTitle'];
    	local BookTitle = A['BookTitle'];
    	local Conference = A['Conference'];
    	local TransTitle = A['TransTitle'];
    	local TitleNote = A['TitleNote'];
    	local TitleLink = A['TitleLink'];
    		if is_set (TitleLink) and false == link_param_ok (TitleLink) then
    			table.insert( z.message_tail, { set_error( 'bad_paramlink', A:ORIGIN('TitleLink'))});		-- url or wikilink in |title-link=;
    		end
    
    	local Chapter = A['Chapter'];
    	local ScriptChapter = A['ScriptChapter'];
    	local ChapterLink	-- = A['ChapterLink'];									-- deprecated as a parameter but still used internally by cite episode
    	local TransChapter = A['TransChapter'];
    	local TitleType = A['TitleType'];
    	local Degree = A['Degree'];
    	local Docket = A['Docket'];
    	local ArchiveFormat = A['ArchiveFormat'];
    	local ArchiveURL = A['ArchiveURL'];
    	local URL = A['URL']
    	local URLorigin = A:ORIGIN('URL');											-- get name of parameter that holds URL
    	local ChapterURL = A['ChapterURL'];
    	local ChapterURLorigin = A:ORIGIN('ChapterURL');							-- get name of parameter that holds ChapterURL
    	local ConferenceFormat = A['ConferenceFormat'];
    	local ConferenceURL = A['ConferenceURL'];
    	local ConferenceURLorigin = A:ORIGIN('ConferenceURL');						-- get name of parameter that holds ConferenceURL
    	local Periodical = A['Periodical'];
    	local Periodical_origin = A:ORIGIN('Periodical');							-- get the name of the periodical parameter
    
    	local Series = A['Series'];
    	
    	local Volume;
    	local Issue;
    	local Page;
    	local Pages;
    	local At;
    
    	if in_array (config.CitationClass, cfg.templates_using_volume) and not ('conference' == config.CitationClass and not is_set (Periodical)) then
    		Volume = A['Volume'];
    	end
    	if in_array (config.CitationClass, cfg.templates_using_issue) and not (in_array (config.CitationClass, {'conference', 'map'}) and not is_set (Periodical))then
    		Issue = A['Issue'];
    	end
    	local Position = '';
    	if not in_array (config.CitationClass, cfg.templates_not_using_page) then
    		Page = A['Page'];
    		Pages = hyphen_to_dash( A['Pages'] );	
    		At = A['At'];
    	end
    
    	local Edition = A['Edition'];
    	local PublicationPlace = A['PublicationPlace']
    	local Place = A['Place'];
    	
    	local PublisherName = A['PublisherName'];
    	local RegistrationRequired = A['RegistrationRequired'];
    		if not is_valid_parameter_value (RegistrationRequired, 'registration', cfg.keywords ['yes_true_y']) then
    			RegistrationRequired=nil;
    		end
    	local SubscriptionRequired = A['SubscriptionRequired'];
    		if not is_valid_parameter_value (SubscriptionRequired, 'subscription', cfg.keywords ['yes_true_y']) then
    			SubscriptionRequired=nil;
    		end
    
    	local Via = A['Via'];
    	local AccessDate = A['AccessDate'];
    	local ArchiveDate = A['ArchiveDate'];
    	local Agency = A['Agency'];
    	local DeadURL = A['DeadURL']
    		if not is_valid_parameter_value (DeadURL, 'dead-url', cfg.keywords ['deadurl']) then	-- set in config.defaults to 'yes'
    			DeadURL = '';														-- anything else, set to empty string
    		end
    
    	local Language = A['Language'];
    	local Format = A['Format'];
    	local ChapterFormat = A['ChapterFormat'];
    	local DoiBroken = A['DoiBroken'];
    	local ID = A['ID'];
    	local ASINTLD = A['ASINTLD'];
    	local IgnoreISBN = A['IgnoreISBN'];
    		if not is_valid_parameter_value (IgnoreISBN, 'ignore-isbn-error', cfg.keywords ['yes_true_y']) then
    			IgnoreISBN = nil;													-- anything else, set to empty string
    		end
    	local Embargo = A['Embargo'];
    	local Class = A['Class'];													-- arxiv class identifier
    
    	local ID_list = extract_ids( args );
    
    	local Quote = A['Quote'];
    
    	local LayFormat = A['LayFormat'];
    	local LayURL = A['LayURL'];
    	local LaySource = A['LaySource'];
    	local Transcript = A['Transcript'];
    	local TranscriptFormat = A['TranscriptFormat'];
    	local TranscriptURL = A['TranscriptURL'] 
    	local TranscriptURLorigin = A:ORIGIN('TranscriptURL');						-- get name of parameter that holds TranscriptURL
    
    	local LastAuthorAmp = A['LastAuthorAmp'];
    		if not is_valid_parameter_value (LastAuthorAmp, 'last-author-amp', cfg.keywords ['yes_true_y']) then
    			LastAuthorAmp = nil;													-- set to empty string
    		end
    	local no_tracking_cats = A['NoTracking'];
    		if not is_valid_parameter_value (no_tracking_cats, 'no-tracking', cfg.keywords ['yes_true_y']) then
    			no_tracking_cats = nil;												-- set to empty string
    		end
    
    --these are used by cite interview
    	local Callsign = A['Callsign'];
    	local City = A['City'];
    	local Program = A['Program'];
    
    --local variables that are not cs1 parameters
    	local use_lowercase;														-- controls capitalization of certain static text
    	local this_page = mw.title.getCurrentTitle();								-- also used for COinS and for language
    	local anchor_year;															-- used in the CITEREF identifier
    	local COinS_date = {};														-- holds date info extracted from |date= for the COinS metadata by Module:Date verification
    
    -- set default parameter values defined by |mode= parameter.  If |mode= is empty or omitted, use CitationClass to set these values
    	local Mode = A['Mode'];
    	if not is_valid_parameter_value (Mode, 'mode', cfg.keywords['mode']) then
    		Mode = '';
    	end
    	local sepc;											-- separator between citation elements for CS1 a period, for CS2, a comma
    	local PostScript;
    	local Ref;
    	sepc, PostScript, Ref = set_style (Mode:lower(), A['PostScript'], A['Ref'], config.CitationClass);
    	use_lowercase = ( sepc == ',' );					-- used to control capitalization for certain static text
    
    --check this page to see if it is in one of the namespaces that cs1 is not supposed to add to the error categories
    	if not is_set (no_tracking_cats) then										-- ignore if we are already not going to categorize this page
    		if in_array (this_page.nsText, cfg.uncategorized_namespaces) then
    			no_tracking_cats = "true";											-- set no_tracking_cats
    		end
    		for _,v in ipairs (cfg.uncategorized_subpages) do						-- cycle through page name patterns
    			if this_page.text:match (v) then									-- test page name against each pattern
    				no_tracking_cats = "true";										-- set no_tracking_cats
    				break;															-- bail out if one is found
    			end
    		end
    	end
    
    -- check for extra |page=, |pages= or |at= parameters. (also sheet and sheets while we're at it)
    	select_one( args, {'page', 'p', 'pp', 'pages', 'at', 'sheet', 'sheets'}, 'redundant_parameters' );		-- this is a dummy call simply to get the error message and category
    
    	local NoPP = A['NoPP'] 
    	if is_set (NoPP) and is_valid_parameter_value (NoPP, 'nopp', cfg.keywords ['yes_true_y']) then
    		NoPP = true;
    	else
    		NoPP = nil;																-- unset, used as a flag later
    	end
    
    	if is_set(Page) then
    		if is_set(Pages) or is_set(At) then
    			Pages = '';															-- unset the others
    			At = '';
    		end
    		extra_text_in_page_check (Page);										-- add this page to maint cat if |page= value begins with what looks like p. or pp.
    	elseif is_set(Pages) then
    		if is_set(At) then
    			At = '';															-- unset
    		end
    		extra_text_in_page_check (Pages);										-- add this page to maint cat if |pages= value begins with what looks like p. or pp.
    	end	
    
    -- both |publication-place= and |place= (|location=) allowed if different
    	if not is_set(PublicationPlace) and is_set(Place) then
    		PublicationPlace = Place;							-- promote |place= (|location=) to |publication-place
    	end
    	
    	if PublicationPlace == Place then Place = ''; end		-- don't need both if they are the same
    	
    --[[
    Parameter remapping for cite encyclopedia:
    When the citation has these parameters:
    	|encyclopedia and |title then map |title to |article and |encyclopedia to |title
    	|encyclopedia and |article then map |encyclopedia to |title
    	|encyclopedia then map |encyclopedia to |title
    
    	|trans_title maps to |trans_chapter when |title is re-mapped
    	|url maps to |chapterurl when |title is remapped
    
    All other combinations of |encyclopedia, |title, and |article are not modified
    
    ]]
    
    local Encyclopedia = A['Encyclopedia'];
    
    	if ( config.CitationClass == "encyclopaedia" ) or ( config.CitationClass == "citation" and is_set (Encyclopedia)) then	-- test code for citation
    		if is_set(Periodical) then												-- Periodical is set when |encyclopedia is set
    			if is_set(Title) or is_set (ScriptTitle) then
    				if not is_set(Chapter) then
    					Chapter = Title;											-- |encyclopedia and |title are set so map |title to |article and |encyclopedia to |title
    					ScriptChapter = ScriptTitle;
    					TransChapter = TransTitle;
    					ChapterURL = URL;
    					if not is_set (ChapterURL) and is_set (TitleLink) then
    						Chapter= '[[' .. TitleLink .. '|' .. Chapter .. ']]';
    					end
    					Title = Periodical;
    					ChapterFormat = Format;
    					Periodical = '';											-- redundant so unset
    					TransTitle = '';
    					URL = '';
    					Format = '';
    					TitleLink = '';
    					ScriptTitle = '';
    				end
    			else																-- |title not set
    				Title = Periodical;												-- |encyclopedia set and |article set or not set so map |encyclopedia to |title
    				Periodical = '';												-- redundant so unset
    			end
    		end
    	end
    
    -- Special case for cite techreport.
    	if (config.CitationClass == "techreport") then								-- special case for cite techreport
    		if is_set(A['Number']) then													-- cite techreport uses 'number', which other citations alias to 'issue'
    			if not is_set(ID) then												-- can we use ID for the "number"?
    				ID = A['Number'];													-- yes, use it
    			else																-- ID has a value so emit error message
    				table.insert( z.message_tail, { set_error('redundant_parameters', {wrap_style ('parameter', 'id') .. ' and ' .. wrap_style ('parameter', 'number')}, true )});
    			end
    		end	
    	end
    
    -- special case for cite interview
    	if (config.CitationClass == "interview") then
    		if is_set(Program) then
    			ID = ' ' .. Program;
    		end
    		if is_set(Callsign) then
    			if is_set(ID) then
    				ID = ID .. sepc .. ' ' .. Callsign;
    			else
    				ID = ' ' .. Callsign;
    			end
    		end
    		if is_set(City) then
    			if is_set(ID) then
    				ID = ID .. sepc .. ' ' .. City;
    			else
    				ID = ' ' .. City;
    			end
    		end
    
    		if is_set(Others) then
    			if is_set(TitleType) then
    				Others = ' ' .. TitleType .. ' with ' .. Others;
    				TitleType = '';
    			else
    				Others = ' ' .. 'Interview with ' .. Others;
    			end
    		else
    			Others = '(Interview)';
    		end
    	end
    
    -- special case for cite mailing list
    	if (config.CitationClass == "mailinglist") then
    		Periodical = A ['MailingList'];
    	elseif 'mailinglist' == A:ORIGIN('Periodical') then
    		Periodical = '';														-- unset because mailing list is only used for cite mailing list
    	end
    
    -- Account for the oddity that is {{cite conference}}, before generation of COinS data.
    	if 'conference' == config.CitationClass then
    		if is_set(BookTitle) then
    			Chapter = Title;
    --			ChapterLink = TitleLink;											-- |chapterlink= is deprecated
    			ChapterURL = URL;
    			ChapterURLorigin = URLorigin;
    			URLorigin = '';
    			ChapterFormat = Format;
    			TransChapter = TransTitle;
    			Title = BookTitle;
    			Format = '';
    --			TitleLink = '';
    			TransTitle = '';
    			URL = '';
    		end
    	elseif 'speech' ~= config.CitationClass then
    		Conference = '';														-- not cite conference or cite speech so make sure this is empty string
    	end
    
    -- cite map oddities
    	local Cartography = "";
    	local Scale = "";
    	local Sheet = A['Sheet'] or '';
    	local Sheets = A['Sheets'] or '';
    	if config.CitationClass == "map" then
    		Chapter = A['Map'];
    		ChapterURL = A['MapURL'];
    		TransChapter = A['TransMap'];
    		ChapterURLorigin = A:ORIGIN('MapURL');
    		ChapterFormat = A['MapFormat'];
    		
    		Cartography = A['Cartography'];
    		if is_set( Cartography ) then
    			Cartography = sepc .. " " .. wrap_msg ('cartography', Cartography, use_lowercase);
    		end		
    		Scale = A['Scale'];
    		if is_set( Scale ) then
    			Scale = sepc .. " " .. Scale;
    		end
    	end
    
    -- Account for the oddities that are {{cite episode}} and {{cite serial}}, before generation of COinS data.
    	if 'episode' == config.CitationClass or 'serial' == config.CitationClass then
    		local AirDate = A['AirDate'];
    		local SeriesLink = A['SeriesLink'];
    			if is_set (SeriesLink) and false == link_param_ok (SeriesLink) then
    				table.insert( z.message_tail, { set_error( 'bad_paramlink', A:ORIGIN('SeriesLink'))});
    			end
    		local Network = A['Network'];
    		local Station = A['Station'];
    		local s, n = {}, {};
    																				-- do common parameters first
    		if is_set(Network) then table.insert(n, Network); end
    		if is_set(Station) then table.insert(n, Station); end
    		ID = table.concat(n, sepc .. ' ');
    		
    		if not is_set (Date) and is_set (AirDate) then							-- promote airdate to date
    			Date = AirDate;
    		end
    
    		if 'episode' == config.CitationClass then								-- handle the oddities that are strictly {{cite episode}}
    			local Season = A['Season'];
    			local SeriesNumber = A['SeriesNumber'];
    
    			if is_set (Season) and is_set (SeriesNumber) then					-- these are mutually exclusive so if both are set
    				table.insert( z.message_tail, { set_error( 'redundant_parameters', {wrap_style ('parameter', 'season') .. ' and ' .. wrap_style ('parameter', 'seriesno')}, true ) } );		-- add error message
    				SeriesNumber = '';												-- unset; prefer |season= over |seriesno=
    			end
    																				-- assemble a table of parts concatenated later into Series
    			if is_set(Season) then table.insert(s, wrap_msg ('season', Season, use_lowercase)); end
    			if is_set(SeriesNumber) then table.insert(s, wrap_msg ('series', SeriesNumber, use_lowercase)); end
    			if is_set(Issue) then table.insert(s, wrap_msg ('episode', Issue, use_lowercase)); end
    			Issue = '';															-- unset because this is not a unique parameter
    	
    			Chapter = Title;													-- promote title parameters to chapter
    			ScriptChapter = ScriptTitle;
    			ChapterLink = TitleLink;											-- alias episodelink
    			TransChapter = TransTitle;
    			ChapterURL = URL;
    			ChapterURLorigin = A:ORIGIN('URL');
    			
    			Title = Series;														-- promote series to title
    			TitleLink = SeriesLink;
    			Series = table.concat(s, sepc .. ' ');								-- this is concatenation of season, seriesno, episode number
    
    			if is_set (ChapterLink) and not is_set (ChapterURL) then			-- link but not URL
    				Chapter = '[[' .. ChapterLink .. '|' .. Chapter .. ']]';		-- ok to wikilink
    			elseif is_set (ChapterLink) and is_set (ChapterURL) then			-- if both are set, URL links episode;
    				Series = '[[' .. ChapterLink .. '|' .. Series .. ']]';			-- series links with ChapterLink (episodelink -> TitleLink -> ChapterLink) ugly
    			end
    			URL = '';															-- unset
    			TransTitle = '';
    			ScriptTitle = '';
    			
    		else																	-- now oddities that are cite serial
    			Issue = '';															-- unset because this parameter no longer supported by the citation/core version of cite serial
    			Chapter = A['Episode'];												-- TODO: make |episode= available to cite episode someday?
    			if is_set (Series) and is_set (SeriesLink) then
    				Series = '[[' .. SeriesLink .. '|' .. Series .. ']]';
    			end
    			Series = wrap_style ('italic-title', Series);						-- series is italicized
    		end	
    	end
    -- end of {{cite episode}} stuff
    
    -- Account for the oddities that are {{cite arxiv}}, before generation of COinS data.
    	if 'arxiv' == config.CitationClass then
    		if not is_set (ID_list['ARXIV']) then									-- |arxiv= or |eprint= required for cite arxiv
    			table.insert( z.message_tail, { set_error( 'arxiv_missing', {}, true ) } );		-- add error message
    		elseif is_set (Series) then												-- series is an alias of version
    			ID_list['ARXIV'] = ID_list['ARXIV'] .. Series;						-- concatenate version onto the end of the arxiv identifier
    			Series = '';														-- unset
    			deprecated_parameter ('version');									-- deprecated parameter but only for cite arxiv
    		end
    		
    		if first_set ({AccessDate, At, Chapter, Format, Page, Pages, Periodical, PublisherName, URL,	-- a crude list of parameters that are not supported by cite arxiv
    			ID_list['ASIN'], ID_list['BIBCODE'], ID_list['DOI'], ID_list['ISBN'], ID_list['ISSN'],
    			ID_list['JFM'], ID_list['JSTOR'], ID_list['LCCN'], ID_list['MR'], ID_list['OCLC'], ID_list['OL'],
    			ID_list['OSTI'], ID_list['PMC'], ID_list['PMID'], ID_list['RFC'], ID_list['SSRN'], ID_list['USENETID'], ID_list['ZBL']},27) then
    				table.insert( z.message_tail, { set_error( 'arxiv_params_not_supported', {}, true ) } );		-- add error message
    
    				AccessDate= '';													-- set these to empty string; not supported in cite arXiv
    				PublisherName = '';												-- (if the article has been published, use cite journal, or other)
    				Chapter = '';
    				URL = '';
    				Format = '';
    				Page = ''; Pages = ''; At = '';
    		end
    		Periodical = 'arXiv';													-- set to arXiv for COinS; after that, must be set to empty string
    	end
    
    -- handle type parameter for those CS1 citations that have default values
    	if in_array(config.CitationClass, {"AV-media-notes", "DVD-notes", "mailinglist", "map", "podcast", "pressrelease", "report", "techreport", "thesis"}) then
    		TitleType = set_titletype (config.CitationClass, TitleType);
    		if is_set(Degree) and "Thesis" == TitleType then						-- special case for cite thesis
    			TitleType = Degree .. " thesis";
    		end
    	end
    
    	if is_set(TitleType) then													-- if type parameter is specified
    	TitleType = substitute( cfg.messages['type'], TitleType);					-- display it in parentheses
    	end
    
    -- legacy: promote concatenation of |month=, and |year= to Date if Date not set; or, promote PublicationDate to Date if neither Date nor Year are set.
    	if not is_set (Date) then
    		Date = Year;															-- promote Year to Date
    		Year = nil;																-- make nil so Year as empty string isn't used for CITEREF
    		if not is_set (Date) and is_set(PublicationDate) then					-- use PublicationDate when |date= and |year= are not set
    			Date = PublicationDate;												-- promote PublicationDate to Date
    			PublicationDate = '';												-- unset, no longer needed
    		end
    	end
    
    	if PublicationDate == Date then PublicationDate = ''; end					-- if PublicationDate is same as Date, don't display in rendered citation
    
    --[[
    Go test all of the date-holding parameters for valid MOS:DATE format and make sure that dates are real dates. This must be done before we do COinS because here is where
    we get the date used in the metadata.
    
    Date validation supporting code is in Module:Citation/CS1/Date_validation
    ]]
    	do	-- create defined block to contain local variables error_message and mismatch
    		local error_message = '';
    																				-- AirDate has been promoted to Date so not necessary to check it
    		anchor_year, error_message = dates({['access-date']=AccessDate, ['archive-date']=ArchiveDate, ['date']=Date, ['doi-broken-date']=DoiBroken,
    			['embargo']=Embargo, ['lay-date']=LayDate, ['publication-date']=PublicationDate, ['year']=Year}, COinS_date);
    
    		if is_set (Year) and is_set (Date) then									-- both |date= and |year= not normally needed; 
    			local mismatch = year_date_check (Year, Date)
    			if 0 == mismatch then												-- |year= does not match a year-value in |date=
    				if is_set (error_message) then									-- if there is already an error message
    					error_message = error_message .. ', ';						-- tack on this additional message
    				end
    				error_message = error_message .. '&#124;year= / &#124;date= mismatch';
    			elseif 1 == mismatch then											-- |year= matches year-value in |date=
    				add_maint_cat ('date_year');
    			end
    		end
    
    		if is_set(error_message) then
    			table.insert( z.message_tail, { set_error( 'bad_date', {error_message}, true ) } );	-- add this error message
    		end
    	end	-- end of do
    
    -- Account for the oddity that is {{cite journal}} with |pmc= set and |url= not set.  Do this after date check but before COInS.
    -- Here we unset Embargo if PMC not embargoed (|embargo= not set in the citation) or if the embargo time has expired. Otherwise, holds embargo date
    	Embargo = is_embargoed (Embargo);											-- 
    
    	if config.CitationClass == "journal" and not is_set(URL) and is_set(ID_list['PMC']) then
    		if not is_set (Embargo) then											-- if not embargoed or embargo has expired
    			URL=cfg.id_handlers['PMC'].prefix .. ID_list['PMC'];				-- set url to be the same as the PMC external link if not embargoed
    			URLorigin = cfg.id_handlers['PMC'].parameters[1];					-- set URLorigin to parameter name for use in error message if citation is missing a |title=
    		end
    	end
    
    -- At this point fields may be nil if they weren't specified in the template use.  We can use that fact.
    	-- Test if citation has no title
    	if	not is_set(Title) and
    		not is_set(TransTitle) and
    		not is_set(ScriptTitle) then
    			if 'episode' == config.CitationClass then							-- special case for cite episode; TODO: is there a better way to do this?
    				table.insert( z.message_tail, { set_error( 'citation_missing_title', {'series'}, true ) } );
    			else
    				table.insert( z.message_tail, { set_error( 'citation_missing_title', {'title'}, true ) } );
    			end
    	end
    	
    	if 'none' == Title and in_array (config.CitationClass, {'journal', 'citation'}) and is_set (Periodical) and 'journal' == A:ORIGIN('Periodical') then	-- special case for journal cites
    		Title = '';																-- set title to empty string
    		add_maint_cat ('untitled');
    	end
    
    	check_for_url ({															-- add error message when any of these parameters contains a URL
    		['title']=Title,
    		[A:ORIGIN('Chapter')]=Chapter,
    		[A:ORIGIN('Periodical')]=Periodical,
    		[A:ORIGIN('PublisherName')] = PublisherName,
    		});
    
    	-- COinS metadata (see <http://ocoins.info/>) for automated parsing of citation information.
    	-- handle the oddity that is cite encyclopedia and {{citation |encyclopedia=something}}. Here we presume that
    	-- when Periodical, Title, and Chapter are all set, then Periodical is the book (encyclopedia) title, Title
    	-- is the article title, and Chapter is a section within the article.  So, we remap 
    	
    	local coins_chapter = Chapter;												-- default assuming that remapping not required
    	local coins_title = Title;													-- et tu
    	if 'encyclopaedia' == config.CitationClass or ('citation' == config.CitationClass and is_set (Encyclopedia)) then
    		if is_set (Chapter) and is_set (Title) and is_set (Periodical) then		-- if all are used then
    			coins_chapter = Title;												-- remap
    			coins_title = Periodical;
    		end
    	end
    	local coins_author = a;														-- default for coins rft.au 
    	if 0 < #c then																-- but if contributor list
    		coins_author = c;														-- use that instead
    	end
    
    	-- this is the function call to COinS()
    	local OCinSoutput = COinS({
    		['Periodical'] = Periodical,
    		['Encyclopedia'] = Encyclopedia,
    		['Chapter'] = make_coins_title (coins_chapter, ScriptChapter),			-- Chapter and ScriptChapter stripped of bold / italic wikimarkup
    		['Map'] = Map,
    		['Degree'] = Degree;													-- cite thesis only
    		['Title'] = make_coins_title (coins_title, ScriptTitle),				-- Title and ScriptTitle stripped of bold / italic wikimarkup
    		['PublicationPlace'] = PublicationPlace,
    		['Date'] = COinS_date.rftdate,											-- COinS_date has correctly formatted date if Date is valid;
    		['Season'] = COinS_date.rftssn,
    		['Chron'] =  COinS_date.rftchron or (not COinS_date.rftdate and Date) or '',	-- chron but if not set and invalid date format use Date; keep this last bit?
    		['Series'] = Series,
    		['Volume'] = Volume,
    		['Issue'] = Issue,
    		['Pages'] = get_coins_pages (first_set ({Sheet, Sheets, Page, Pages, At}, 5)),				-- pages stripped of external links
    		['Edition'] = Edition,
    		['PublisherName'] = PublisherName,
    		['URL'] = first_set ({ChapterURL, URL}, 2),
    		['Authors'] = coins_author,
    		['ID_list'] = ID_list,
    		['RawPage'] = this_page.prefixedText,
    	}, config.CitationClass);
    
    -- Account for the oddities that are {{cite arxiv}}, AFTER generation of COinS data.
    	if 'arxiv' == config.CitationClass then										-- we have set rft.jtitle in COinS to arXiv, now unset so it isn't displayed
    		Periodical = '';														-- periodical not allowed in cite arxiv; if article has been published, use cite journal
    	end
    
    -- special case for cite newsgroup.  Do this after COinS because we are modifying Publishername to include some static text
    	if 'newsgroup' == config.CitationClass then
    		if is_set (PublisherName) then
    			PublisherName = substitute (cfg.messages['newsgroup'], external_link( 'news:' .. PublisherName, PublisherName, A:ORIGIN('PublisherName') ));
    		end
    	end
    
    
    
    	-- Now perform various field substitutions.
    	-- We also add leading spaces and surrounding markup and punctuation to the
    	-- various parts of the citation, but only when they are non-nil.
    	local EditorCount;															-- used only for choosing {ed.) or (eds.) annotation at end of editor name-list
    	do
    		local last_first_list;
    		local maximum;
    		local control = { 
    			format = NameListFormat,											-- empty string or 'vanc'
    			maximum = nil,														-- as if display-authors or display-editors not set
    			lastauthoramp = LastAuthorAmp,
    			page_name = this_page.text											-- get current page name so that we don't wikilink to it via editorlinkn
    		};
    
    		do																		-- do editor name list first because coauthors can modify control table
    			maximum , editor_etal = get_display_authors_editors (A['DisplayEditors'], #e, 'editors', editor_etal);
    			-- Preserve old-style implicit et al.
    			if not is_set(maximum) and #e == 4 then 
    				maximum = 3;
    				table.insert( z.message_tail, { set_error('implict_etal_editor', {}, true) } );
    			end
    
    			control.maximum = maximum;
    			
    			last_first_list, EditorCount = list_people(control, e, editor_etal, 'editor');
    
    			if is_set (Editors) then
    				if editor_etal then
    					Editors = Editors .. ' ' .. cfg.messages['et al'];			-- add et al. to editors parameter beause |display-editors=etal
    					EditorCount = 2;											-- with et al., |editors= is multiple names; spoof to display (eds.) annotation
    				else
    					EditorCount = 2;											-- we don't know but assume |editors= is multiple names; spoof to display (eds.) annotation
    				end
    			else
    				Editors = last_first_list;										-- either an author name list or an empty string
    			end
    
    			if 1 == EditorCount and (true == editor_etal or 1 < #e) then		-- only one editor displayed but includes etal then 
    				EditorCount = 2;												-- spoof to display (eds.) annotation
    			end
    		end
    		do																		-- now do translators
    			control.maximum = #t;												-- number of translators
    			Translators = list_people(control, t, false, 'translator');			-- et al not currently supported
    		end
    		do																		-- now do contributors
    			control.maximum = #c;												-- number of contributors
    			Contributors = list_people(control, c, false, 'contributor');		-- et al not currently supported
    		end
    		do																		-- now do authors
    			control.maximum , author_etal = get_display_authors_editors (A['DisplayAuthors'], #a, 'authors', author_etal);
    
    			if is_set(Coauthors) then											-- if the coauthor field is also used, prevent ampersand and et al. formatting.
    				control.lastauthoramp = nil;
    				control.maximum = #a + 1;
    			end
    			
    			last_first_list = list_people(control, a, author_etal, 'author');
    
    			if is_set (Authors) then
    				Authors, author_etal = name_has_etal (Authors, author_etal, false);	-- find and remove variations on et al.
    				if author_etal then
    					Authors = Authors .. ' ' .. cfg.messages['et al'];			-- add et al. to authors parameter
    				end
    			else
    				Authors = last_first_list;										-- either an author name list or an empty string
    			end
    		end																		-- end of do
    
    		if not is_set(Authors) and is_set(Coauthors) then						-- coauthors aren't displayed if one of authors=, authorn=, or lastn= isn't specified
    			table.insert( z.message_tail, { set_error('coauthors_missing_author', {}, true) } );	-- emit error message
    		end
    	end
    
    -- apply |[xx-]format= styling; at the end, these parameters hold correctly styled format annotation,
    -- an error message if the associated url is not set, or an empty string for concatenation
    	ArchiveFormat = style_format (ArchiveFormat, ArchiveURL, 'archive-format', 'archive-url');
    	ConferenceFormat = style_format (ConferenceFormat, ConferenceURL, 'conference-format', 'conference-url');
    	Format = style_format (Format, URL, 'format', 'url');
    	LayFormat = style_format (LayFormat, LayURL, 'lay-format', 'lay-url');
    	TranscriptFormat = style_format (TranscriptFormat, TranscriptURL, 'transcript-format', 'transcripturl');
    
    -- special case for chapter format so no error message or cat when chapter not supported
    	if not (in_array(config.CitationClass, {'web','news','journal', 'magazine', 'pressrelease','podcast', 'newsgroup', 'arxiv'}) or
    		('citation' == config.CitationClass and is_set (Periodical) and not is_set (Encyclopedia))) then
    			ChapterFormat = style_format (ChapterFormat, ChapterURL, 'chapter-format', 'chapter-url');
    	end
    
    	if  not is_set(URL) then --and
    		if in_array(config.CitationClass, {"web","podcast", "mailinglist"}) then		-- Test if cite web or cite podcast |url= is missing or empty 
    			table.insert( z.message_tail, { set_error( 'cite_web_url', {}, true ) } );
    		end
    		
    		-- Test if accessdate is given without giving a URL
    		if is_set(AccessDate) and not is_set(ChapterURL)then					-- ChapterURL may be set when the others are not set; TODO: move this to a separate test?
    			table.insert( z.message_tail, { set_error( 'accessdate_missing_url', {}, true ) } );
    			AccessDate = '';
    		end
    	end
    
    	local OriginalURL, OriginalURLorigin, OriginalFormat;						-- TODO: swap chapter and title here so that archive applies to most specific if both are set?
    	DeadURL = DeadURL:lower();													-- used later when assembling archived text
    	if is_set( ArchiveURL ) then
    		if is_set (URL) then
    			OriginalURL = URL;													-- save copy of original source URL
    			OriginalURLorigin = URLorigin;										-- name of url parameter for error messages
    			OriginalFormat = Format;											-- and original |format=
    			if 'no' ~= DeadURL then												-- if URL set then archive-url applies to it
    				URL = ArchiveURL												-- swap-in the archive's url
    				URLorigin = A:ORIGIN('ArchiveURL')								-- name of archive url parameter for error messages
    				Format = ArchiveFormat or '';									-- swap in archive's format
    			end
    		elseif is_set (ChapterURL) then 										-- URL not set so if chapter-url is set apply archive url to it
    			OriginalURL = ChapterURL;											-- save copy of source chapter's url for archive text
    			OriginalURLorigin = ChapterURLorigin;								-- name of chapter-url parameter for error messages
    			OriginalFormat = ChapterFormat;										-- and original |format=
    			if 'no' ~= DeadURL then
    				ChapterURL = ArchiveURL											-- swap-in the archive's url
    				ChapterURLorigin = A:ORIGIN('ArchiveURL')						-- name of archive-url parameter for error messages
    				ChapterFormat = ArchiveFormat or '';							-- swap in archive's format
    			end
    		end
    	end
    
    	if in_array(config.CitationClass, {'web','news','journal', 'magazine', 'pressrelease','podcast', 'newsgroup', 'arxiv'}) or	-- if any of the 'periodical' cites except encyclopedia
    		('citation' == config.CitationClass and is_set (Periodical) and not is_set (Encyclopedia)) then
    			local chap_param;
    			if is_set (Chapter) then											-- get a parameter name from one of these chapter related meta-parameters
    				chap_param = A:ORIGIN ('Chapter')
    			elseif is_set (TransChapter) then
    				chap_param = A:ORIGIN ('TransChapter')
    			elseif is_set (ChapterURL) then
    				chap_param = A:ORIGIN ('ChapterURL')
    			elseif is_set (ScriptChapter) then
    				chap_param = A:ORIGIN ('ScriptChapter')
    			else is_set (ChapterFormat)
    				chap_param = A:ORIGIN ('ChapterFormat')
    			end
    
    			if is_set (chap_param) then											-- if we found one
    				table.insert( z.message_tail, { set_error( 'chapter_ignored', {chap_param}, true ) } );		-- add error message
    				Chapter = '';													-- and set them to empty string to be safe with concatenation
    				TransChapter = '';
    				ChapterURL = '';
    				ScriptChapter = '';
    				ChapterFormat = '';
    			end
    	else																		-- otherwise, format chapter / article title
    		local no_quotes = false;												-- default assume that we will be quoting the chapter parameter value
    		if is_set (Contribution) and 0 < #c then								-- if this is a contribution with contributor(s)
    			if in_array (Contribution:lower(), cfg.keywords.contribution) then	-- and a generic contribution title
    				no_quotes = true;												-- then render it unquoted
    			end
    		end
    
    		Chapter = format_chapter_title (ScriptChapter, Chapter, TransChapter, ChapterURL, ChapterURLorigin, no_quotes);		-- Contribution is also in Chapter
    		if is_set (Chapter) then
    			if 'map' == config.CitationClass and is_set (TitleType) then
    				Chapter = Chapter .. ' ' .. TitleType;
    			end
    			Chapter = Chapter .. ChapterFormat .. sepc .. ' ';
    		elseif is_set (ChapterFormat) then										-- |chapter= not set but |chapter-format= is so ...
    			Chapter = ChapterFormat .. sepc .. ' ';								-- ... ChapterFormat has error message, we want to see it
    		end
    	end
    
    	-- Format main title.
    	if is_set(TitleLink) and is_set(Title) then
    		Title = "[[" .. TitleLink .. "|" .. Title .. "]]"
    	end
    
    	if in_array(config.CitationClass, {'web','news','journal', 'magazine', 'pressrelease','podcast', 'newsgroup', 'mailinglist', 'arxiv'}) or
    		('citation' == config.CitationClass and is_set (Periodical) and not is_set (Encyclopedia)) or
    		('map' == config.CitationClass and is_set (Periodical)) then			-- special case for cite map when the map is in a periodical treat as an article
    			Title = kern_quotes (Title);										-- if necessary, separate title's leading and trailing quote marks from Module provided quote marks
    			Title = wrap_style ('quoted-title', Title);
    	
    			Title = script_concatenate (Title, ScriptTitle);					-- <bdi> tags, lang atribute, categorization, etc; must be done after title is wrapped
    			TransTitle= wrap_style ('trans-quoted-title', TransTitle );
    	elseif 'report' == config.CitationClass then								-- no styling for cite report
    		Title = script_concatenate (Title, ScriptTitle);						-- <bdi> tags, lang atribute, categorization, etc; must be done after title is wrapped
    		TransTitle= wrap_style ('trans-quoted-title', TransTitle );				-- for cite report, use this form for trans-title
    	else
    		Title = wrap_style ('italic-title', Title);
    		Title = script_concatenate (Title, ScriptTitle);						-- <bdi> tags, lang atribute, categorization, etc; must be done after title is wrapped
    		TransTitle = wrap_style ('trans-italic-title', TransTitle);
    	end
    
    	TransError = "";
    	if is_set(TransTitle) then
    		if is_set(Title) then
    			TransTitle = " " .. TransTitle;
    		else
    			TransError = " " .. set_error( 'trans_missing_title', {'title'} );
    		end
    	end
    	
    	Title = Title .. TransTitle;
    	
    	if is_set(Title) then
    		if not is_set(TitleLink) and is_set(URL) then 
    			Title = external_link( URL, Title, URLorigin ) .. TransError .. Format;
    			URL = "";
    			Format = "";
    		else
    			Title = Title .. TransError;
    		end
    	end
    
    	if is_set(Place) then
    		Place = " " .. wrap_msg ('written', Place, use_lowercase) .. sepc .. " ";
    	end
    
    	if is_set (Conference) then
    		if is_set (ConferenceURL) then
    			Conference = external_link( ConferenceURL, Conference, ConferenceURLorigin );
    		end
    		Conference = sepc .. " " .. Conference .. ConferenceFormat;
    	elseif is_set(ConferenceURL) then
    		Conference = sepc .. " " .. external_link( ConferenceURL, nil, ConferenceURLorigin );
    	end
    
    	if not is_set(Position) then
    		local Minutes = A['Minutes'];
    		local Time = A['Time'];
    
    		if is_set(Minutes) then
    			if is_set (Time) then
    				table.insert( z.message_tail, { set_error( 'redundant_parameters', {wrap_style ('parameter', 'minutes') .. ' and ' .. wrap_style ('parameter', 'time')}, true ) } );
    			end
    			Position = " " .. Minutes .. " " .. cfg.messages['minutes'];
    		else
    			if is_set(Time) then
    				local TimeCaption = A['TimeCaption']
    				if not is_set(TimeCaption) then
    					TimeCaption = cfg.messages['event'];
    					if sepc ~= '.' then
    						TimeCaption = TimeCaption:lower();
    					end
    				end
    				Position = " " .. TimeCaption .. " " .. Time;
    			end
    		end
    	else
    		Position = " " .. Position;
    		At = '';
    	end
    
    	Page, Pages, Sheet, Sheets = format_pages_sheets (Page, Pages, Sheet, Sheets, config.CitationClass, Periodical_origin, sepc, NoPP, use_lowercase);
    
    	At = is_set(At) and (sepc .. " " .. At) or "";
    	Position = is_set(Position) and (sepc .. " " .. Position) or "";
    	if config.CitationClass == 'map' then
    		local Section = A['Section'];
    		local Sections = A['Sections'];
    		local Inset = A['Inset'];
    		
    		if is_set( Inset ) then
    			Inset = sepc .. " " .. wrap_msg ('inset', Inset, use_lowercase);
    		end			
    
    		if is_set( Sections ) then
    			Section = sepc .. " " .. wrap_msg ('sections', Sections, use_lowercase);
    		elseif is_set( Section ) then
    			Section = sepc .. " " .. wrap_msg ('section', Section, use_lowercase);
    		end
    		At = At .. Inset .. Section;		
    	end	
    
    	if is_set (Language) then
    		Language = language_parameter (Language);								-- format, categories, name from ISO639-1, etc
    	else
    		Language="";															-- language not specified so make sure this is an empty string;
    	end
    
    	Others = is_set(Others) and (sepc .. " " .. Others) or "";
    	
    	if is_set (Translators) then
    		Others = sepc .. ' Translated by ' .. Translators .. Others; 
    	end
    
    	TitleNote = is_set(TitleNote) and (sepc .. " " .. TitleNote) or "";
    	if is_set (Edition) then
    		if Edition:match ('%f[%a][Ee]d%.?$') or Edition:match ('%f[%a][Ee]dition$') then
    			add_maint_cat ('extra_text', 'edition');
    		end
    		Edition = " " .. wrap_msg ('edition', Edition);
    	else
    		Edition = '';
    	end
    
    	Series = is_set(Series) and (sepc .. " " .. Series) or "";
    	OrigYear = is_set(OrigYear) and (" [" .. OrigYear .. "]") or "";
    	Agency = is_set(Agency) and (sepc .. " " .. Agency) or "";
    
    	Volume = format_volume_issue (Volume, Issue, config.CitationClass, Periodical_origin, sepc, use_lowercase);
    
    	------------------------------------ totally unrelated data
    	if is_set(Via) then
    		Via = " " .. wrap_msg ('via', Via);
    	end
    
    --[[
    Subscription implies paywall; Registration does not.  If both are used in a citation, the subscription required link
    note is displayed. There are no error messages for this condition.
    
    ]]
    	if is_set (SubscriptionRequired) then
    		SubscriptionRequired = sepc .. " " .. cfg.messages['subscription'];		-- subscription required message
    	elseif is_set (RegistrationRequired) then
    		SubscriptionRequired = sepc .. " " .. cfg.messages['registration'];		-- registration required message
    	else
    		SubscriptionRequired = '';												-- either or both might be set to something other than yes true y
    	end
    
    	if is_set(AccessDate) then
    		local retrv_text = " " .. cfg.messages['retrieved']
    
    		AccessDate = nowrap_date (AccessDate);									-- wrap in nowrap span if date in appropriate format
    		if (sepc ~= ".") then retrv_text = retrv_text:lower() end				-- if 'citation', lower case
    		AccessDate = substitute (retrv_text, AccessDate);						-- add retrieved text
    																				-- neither of these work; don't know why; it seems that substitute() isn't being called	
    		AccessDate = substitute (cfg.presentation['accessdate'], {sepc, AccessDate});	-- allow editors to hide accessdates
    	end
    	
    	if is_set(ID) then ID = sepc .." ".. ID; end
       	if "thesis" == config.CitationClass and is_set(Docket) then
    		ID = sepc .." Docket ".. Docket .. ID;
    	end
       	if "report" == config.CitationClass and is_set(Docket) then					-- for cite report when |docket= is set
    		ID = sepc .. ' ' .. Docket;												-- overwrite ID even if |id= is set
    	end
    
    	ID_list = build_id_list( ID_list, {DoiBroken = DoiBroken, ASINTLD = ASINTLD, IgnoreISBN = IgnoreISBN, Embargo=Embargo, Class = Class} );
    
    	if is_set(URL) then
    		URL = " " .. external_link( URL, nil, URLorigin );
    	end
    
    	if is_set(Quote) then
    		if Quote:sub(1,1) == '"' and Quote:sub(-1,-1) == '"' then				-- if first and last characters of quote are quote marks
    			Quote = Quote:sub(2,-2);											-- strip them off
    		end
    		Quote = sepc .." " .. wrap_style ('quoted-text', Quote ); 				-- wrap in <q>...</q> tags
    		PostScript = "";														-- cs1|2 does not supply terminal punctuation when |quote= is set
    	end
    	
    	local Archived
    	if is_set(ArchiveURL) then
    		if not is_set(ArchiveDate) then
    			ArchiveDate = set_error('archive_missing_date');
    		end
    		if "no" == DeadURL then
    			local arch_text = cfg.messages['archived'];
    			if sepc ~= "." then arch_text = arch_text:lower() end
    			Archived = sepc .. " " .. substitute( cfg.messages['archived-not-dead'],
    				{ external_link( ArchiveURL, arch_text, A:ORIGIN('ArchiveURL') ) .. ArchiveFormat, ArchiveDate } );
    			if not is_set(OriginalURL) then
    				Archived = Archived .. " " .. set_error('archive_missing_url');							   
    			end
    		elseif is_set(OriginalURL) then											-- DeadURL is empty, 'yes', 'true', 'y', 'unfit', 'usurped'
    			local arch_text = cfg.messages['archived-dead'];
    			if sepc ~= "." then arch_text = arch_text:lower() end
    			if in_array (DeadURL, {'unfit', 'usurped'}) then
    				Archived = sepc .. " " .. 'Archived from the original on ' .. ArchiveDate;	-- format already styled
    			else																-- DeadURL is empty, 'yes', 'true', or 'y'
    				Archived = sepc .. " " .. substitute( arch_text,
    					{ external_link( OriginalURL, cfg.messages['original'], OriginalURLorigin ) .. OriginalFormat, ArchiveDate } );	-- format already styled
    			end	
    		else
    			local arch_text = cfg.messages['archived-missing'];
    			if sepc ~= "." then arch_text = arch_text:lower() end
    			Archived = sepc .. " " .. substitute( arch_text, 
    				{ set_error('archive_missing_url'), ArchiveDate } );
    		end
    	elseif is_set (ArchiveFormat) then
    		Archived = ArchiveFormat;												-- if set and ArchiveURL not set ArchiveFormat has error message
    	else
    		Archived = ""
    	end
    	
    	local Lay = '';
    	if is_set(LayURL) then
    		if is_set(LayDate) then LayDate = " (" .. LayDate .. ")" end
    		if is_set(LaySource) then 
    			LaySource = " &ndash; ''" .. safe_for_italics(LaySource) .. "''";
    		else
    			LaySource = "";
    		end
    		if sepc == '.' then
    			Lay = sepc .. " " .. external_link( LayURL, cfg.messages['lay summary'], A:ORIGIN('LayURL') ) .. LayFormat .. LaySource .. LayDate
    		else
    			Lay = sepc .. " " .. external_link( LayURL, cfg.messages['lay summary']:lower(), A:ORIGIN('LayURL') ) .. LayFormat .. LaySource .. LayDate
    		end			
    	elseif is_set (LayFormat) then												-- Test if |lay-format= is given without giving a |lay-url=
    		Lay = sepc .. LayFormat;												-- if set and LayURL not set, then LayFormat has error message
    	end
    
    	if is_set(Transcript) then
    		if is_set(TranscriptURL) then
    			Transcript = external_link( TranscriptURL, Transcript, TranscriptURLorigin );
    		end
    		Transcript = sepc .. ' ' .. Transcript .. TranscriptFormat;
    	elseif is_set(TranscriptURL) then
    		Transcript = external_link( TranscriptURL, nil, TranscriptURLorigin );
    	end
    
    	local Publisher;
    	if is_set(Periodical) and
    		not in_array(config.CitationClass, {"encyclopaedia","web","pressrelease","podcast"}) then
    		if is_set(PublisherName) then
    			if is_set(PublicationPlace) then
    				Publisher = PublicationPlace .. ": " .. PublisherName;
    			else
    				Publisher = PublisherName;  
    			end
    		elseif is_set(PublicationPlace) then
    			Publisher= PublicationPlace;
    		else 
    			Publisher = "";
    		end
    		if is_set(PublicationDate) then
    			if is_set(Publisher) then
    				Publisher = Publisher .. ", " .. wrap_msg ('published', PublicationDate);
    			else
    				Publisher = PublicationDate;
    			end
    		end
    		if is_set(Publisher) then
    			Publisher = " (" .. Publisher .. ")";
    		end
    	else
    		if is_set(PublicationDate) then
    			PublicationDate = " (" .. wrap_msg ('published', PublicationDate) .. ")";
    		end
    		if is_set(PublisherName) then
    			if is_set(PublicationPlace) then
    				Publisher = sepc .. " " .. PublicationPlace .. ": " .. PublisherName .. PublicationDate;
    			else
    				Publisher = sepc .. " " .. PublisherName .. PublicationDate;  
    			end			
    		elseif is_set(PublicationPlace) then 
    			Publisher= sepc .. " " .. PublicationPlace .. PublicationDate;
    		else 
    			Publisher = PublicationDate;
    		end
    	end
    	
    	-- Several of the above rely upon detecting this as nil, so do it last.
    	if is_set(Periodical) then
    		if is_set(Title) or is_set(TitleNote) then 
    			Periodical = sepc .. " " .. wrap_style ('italic-title', Periodical) 
    		else 
    			Periodical = wrap_style ('italic-title', Periodical)
    		end
    	end
    
    --[[
    Handle the oddity that is cite speech.  This code overrides whatever may be the value assigned to TitleNote (through |department=) and forces it to be " (Speech)" so that
    the annotation directly follows the |title= parameter value in the citation rather than the |event= parameter value (if provided).
    ]]
    	if "speech" == config.CitationClass then				-- cite speech only
    		TitleNote = " (Speech)";							-- annotate the citation
    		if is_set (Periodical) then							-- if Periodical, perhaps because of an included |website= or |journal= parameter 
    			if is_set (Conference) then						-- and if |event= is set
    				Conference = Conference .. sepc .. " ";		-- then add appropriate punctuation to the end of the Conference variable before rendering
    			end
    		end
    	end
    
    	-- Piece all bits together at last.  Here, all should be non-nil.
    	-- We build things this way because it is more efficient in LUA
    	-- not to keep reassigning to the same string variable over and over.
    
    	local tcommon;
    	local tcommon2;																-- used for book cite when |contributor= is set
    	
    	if in_array(config.CitationClass, {"journal","citation"}) and is_set(Periodical) then
    		if is_set(Others) then Others = Others .. sepc .. " " end
    		tcommon = safe_join( {Others, Title, TitleNote, Conference, Periodical, Format, TitleType, Series, 
    			Language, Edition, Publisher, Agency, Volume}, sepc );
    		
    	elseif in_array(config.CitationClass, {"book","citation"}) and not is_set(Periodical) then		-- special cases for book cites
    		if is_set (Contributors) then											-- when we are citing foreword, preface, introduction, etc
    			tcommon = safe_join( {Title, TitleNote}, sepc );					-- author and other stuff will come after this and before tcommon2
    			tcommon2 = safe_join( {Conference, Periodical, Format, TitleType, Series, Language, Volume, Others, Edition, Publisher, Agency}, sepc );
    		else
    			tcommon = safe_join( {Title, TitleNote, Conference, Periodical, Format, TitleType, Series, Language, Volume, Others, Edition, Publisher, Agency}, sepc );
    		end
    
    	elseif 'map' == config.CitationClass then									-- special cases for cite map
    		if is_set (Chapter) then												-- map in a book; TitleType is part of Chapter
    			tcommon = safe_join( {Title, Format, Edition, Scale, Series, Language, Cartography, Others, Publisher, Volume}, sepc );
    		elseif is_set (Periodical) then											-- map in a periodical
    			tcommon = safe_join( {Title, TitleType, Format, Periodical, Scale, Series, Language, Cartography, Others, Publisher, Volume}, sepc );
    		else																	-- a sheet or stand-alone map
    			tcommon = safe_join( {Title, TitleType, Format, Edition, Scale, Series, Language, Cartography, Others, Publisher}, sepc );
    		end
    		
    	elseif 'episode' == config.CitationClass then								-- special case for cite episode
    		tcommon = safe_join( {Title, TitleNote, TitleType, Series, Transcript, Language, Edition, Publisher}, sepc );
    	else																		-- all other CS1 templates
    		tcommon = safe_join( {Title, TitleNote, Conference, Periodical, Format, TitleType, Series, Language, 
    			Volume, Others, Edition, Publisher, Agency}, sepc );
    	end
    	
    	if #ID_list > 0 then
    		ID_list = safe_join( { sepc .. " ",  table.concat( ID_list, sepc .. " " ), ID }, sepc );
    	else
    		ID_list = ID;
    	end
    	
    	local idcommon = safe_join( { ID_list, URL, Archived, AccessDate, Via, SubscriptionRequired, Lay, Quote }, sepc );
    	local text;
    	local pgtext = Position .. Sheet .. Sheets .. Page .. Pages .. At;
    
    	if is_set(Date) then
    		if is_set (Authors) or is_set (Editors) then							-- date follows authors or editors when authors not set
    			Date = " (" .. Date ..")" .. OrigYear .. sepc .. " ";				-- in paranetheses
    		else																	-- neither of authors and editors set
    			if (string.sub(tcommon,-1,-1) == sepc) then							-- if the last character of tcommon is sepc
    				Date = " " .. Date .. OrigYear;									-- Date does not begin with sepc
    			else
    				Date = sepc .. " " .. Date .. OrigYear;							-- Date begins with sepc
    			end
    		end
    	end	
    	if is_set(Authors) then
    		if is_set(Coauthors) then
    			if 'vanc' == NameListFormat then									-- separate authors and coauthors with proper name-list-separator
    				Authors = Authors .. ', ' .. Coauthors;
    			else
    				Authors = Authors .. '; ' .. Coauthors;
    			end
    		end
    		if not is_set (Date) then												-- when date is set it's in parentheses; no Authors termination
    			Authors = terminate_name_list (Authors, sepc);						-- when no date, terminate with 0 or 1 sepc and a space
    		end
    		if is_set(Editors) then
    			local in_text = " ";
    			local post_text = "";
    			if is_set(Chapter) and 0 == #c then
    				in_text = in_text .. cfg.messages['in'] .. " "
    				if (sepc ~= '.') then in_text = in_text:lower() end				-- lowercase for cs2
    			else
    				if EditorCount <= 1 then
    					post_text = ", " .. cfg.messages['editor'];
    				else
    					post_text = ", " .. cfg.messages['editors'];
    				end
    			end 
    			Editors = terminate_name_list (in_text .. Editors .. post_text, sepc);	-- terminate with 0 or 1 sepc and a space
    		end
    		if is_set (Contributors) then											-- book cite and we're citing the intro, preface, etc
    			local by_text = sepc .. ' ' .. cfg.messages['by'] .. ' ';
    			if (sepc ~= '.') then by_text = by_text:lower() end					-- lowercase for cs2
    			Authors = by_text .. Authors;										-- author follows title so tweak it here
    			if is_set (Editors) then											-- when Editors make sure that Authors gets terminated
    				Authors = terminate_name_list (Authors, sepc);					-- terminate with 0 or 1 sepc and a space
    			end
    			if not is_set (Date) then											-- when date is set it's in parentheses; no Contributors termination
    				Contributors = terminate_name_list (Contributors, sepc);		-- terminate with 0 or 1 sepc and a space
    			end
    			text = safe_join( {Contributors, Date, Chapter, tcommon, Authors, Place, Editors, tcommon2, pgtext, idcommon }, sepc );
    		else
    			text = safe_join( {Authors, Date, Chapter, Place, Editors, tcommon, pgtext, idcommon }, sepc );
    		end
    	elseif is_set(Editors) then
    		if is_set(Date) then
    			if EditorCount <= 1 then
    				Editors = Editors .. ", " .. cfg.messages['editor'];
    			else
    				Editors = Editors .. ", " .. cfg.messages['editors'];
    			end
    		else
    			if EditorCount <= 1 then
    				Editors = Editors .. " (" .. cfg.messages['editor'] .. ")" .. sepc .. " "
    			else
    				Editors = Editors .. " (" .. cfg.messages['editors'] .. ")" .. sepc .. " "
    			end
    		end
    		text = safe_join( {Editors, Date, Chapter, Place, tcommon, pgtext, idcommon}, sepc );
    	else
    		if config.CitationClass=="journal" and is_set(Periodical) then
    			text = safe_join( {Chapter, Place, tcommon, pgtext, Date, idcommon}, sepc );
    		else
    			text = safe_join( {Chapter, Place, tcommon, Date, pgtext, idcommon}, sepc );
    		end
    	end
    	
    	if is_set(PostScript) and PostScript ~= sepc then
    		text = safe_join( {text, sepc}, sepc );  --Deals with italics, spaces, etc.
    		text = text:sub(1,-sepc:len()-1);
    	end	
    	
    	text = safe_join( {text, PostScript}, sepc );
    
    	-- Now enclose the whole thing in a <cite/> element
    	local options = {};
    	
    	if is_set(config.CitationClass) and config.CitationClass ~= "citation" then
    		options.class = config.CitationClass;
    		options.class = "citation " .. config.CitationClass;					-- class=citation required for blue highlight when used with |ref=
    	else
    		options.class = "citation";
    	end
    	
    	if is_set(Ref) and Ref:lower() ~= "none" then								-- set reference anchor if appropriate
    		local id = Ref
    		if ('harv' == Ref ) then
    			local namelist = {};												-- holds selected contributor, author, editor name list
    --			local year = first_set (Year, anchor_year);							-- Year first for legacy citations and for YMD dates that require disambiguation
    			local year = first_set ({Year, anchor_year}, 2);					-- Year first for legacy citations and for YMD dates that require disambiguation
    
    			if #c > 0 then														-- if there is a contributor list
    				namelist = c;													-- select it
    			elseif #a > 0 then													-- or an author list
    				namelist = a;
    			elseif #e > 0 then													-- or an editor list
    				namelist = e;
    			end
    			id = anchor_id (namelist, year);									-- go make the CITEREF anchor
    		end
    		options.id = id;
    	end
    	
    	if string.len(text:gsub("<span[^>/]*>.-</span>", ""):gsub("%b<>","")) <= 2 then
    		z.error_categories = {};
    		text = set_error('empty_citation');
    		z.message_tail = {};
    	end
    	
    	if is_set(options.id) then 
    		text = '<cite id="' .. mw.uri.anchorEncode(options.id) ..'" class="' .. mw.text.nowiki(options.class) .. '">' .. text .. "</cite>";
    	else
    		text = '<cite class="' .. mw.text.nowiki(options.class) .. '">' .. text .. "</cite>";
    	end		
    
    	local empty_span = '<span style="display:none;">&nbsp;</span>';
    	
    	-- Note: Using display: none on the COinS span breaks some clients.
    	local OCinS = '<span title="' .. OCinSoutput .. '" class="Z3988">' .. empty_span .. '</span>';
    	text = text .. OCinS;
    	
    	if #z.message_tail ~= 0 then
    		text = text .. " ";
    		for i,v in ipairs( z.message_tail ) do
    			if is_set(v[1]) then
    				if i == #z.message_tail then
    					text = text .. error_comment( v[1], v[2] );
    				else
    					text = text .. error_comment( v[1] .. "; ", v[2] );
    				end
    			end
    		end
    	end
    
    	if #z.maintenance_cats ~= 0 then
    		text = text .. '<span class="citation-comment" style="display:none; color:#33aa33">';
    		for _, v in ipairs( z.maintenance_cats ) do								-- append maintenance categories
    			text = text .. ' ' .. v .. ' ([[:Category:' .. v ..'|link]])';
    		end
    		text = text .. '</span>';	-- maintenance mesages (realy just the names of the categories for now)
    	end
    	
    	no_tracking_cats = no_tracking_cats:lower();
    	if in_array(no_tracking_cats, {"", "no", "false", "n"}) then
    		for _, v in ipairs( z.error_categories ) do
    			text = text .. '[[Category:' .. v ..']]';
    		end
    		for _, v in ipairs( z.maintenance_cats ) do								-- append maintenance categories
    			text = text .. '[[Category:' .. v ..']]';
    		end
    		for _, v in ipairs( z.properties_cats ) do								-- append maintenance categories
    			text = text .. '[[Category:' .. v ..']]';
    		end
    	end
    	
    	return text
    end
    
    --[[--------------------------< H A S _ I N V I S I B L E _ C H A R S >----------------------------------------
    
    This function searches a parameter's value for nonprintable or invisible characters.  The search stops at the first match.
    
    Sometime after this module is done with rendering a citation, some C0 control characters are replaced with the
    replacement character.  That replacement character is not detected by this test though it is visible to readers
    of the rendered citation.  This function will detect the replacement character when it is part of the wikisource.
    
    Output of this function is an error message that identifies the character or the Unicode group that the character
    belongs to along with its position in the parameter value.
    
    ]]
    --[[
    local function has_invisible_chars (param, v)
    	local position = '';
    	local i=1;
    
    	while cfg.invisible_chars[i] do
    		local char=cfg.invisible_chars[i][1]									-- the character or group name
    		local pattern=cfg.invisible_chars[i][2]									-- the pattern used to find it
    		v = mw.text.unstripNoWiki( v );											-- remove nowiki stripmarkers
    		position = mw.ustring.find (v, pattern)									-- see if the parameter value contains characters that match the pattern
    		if position then
    			table.insert( z.message_tail, { set_error( 'invisible_char', {char, wrap_style ('parameter', param), position}, true ) } );	-- add error message
    			return;																-- and done with this parameter
    		end
    		i=i+1;																	-- bump our index
    	end
    end
    ]]
    
    --[[--------------------------< Z . C I T A T I O N >----------------------------------------------------------
    
    This is used by templates such as {{cite book}} to create the actual citation text.
    
    ]]
    
    function z.citation(frame)
    	local pframe = frame:getParent()
    	local validation;
    	
    	if nil ~= string.find (frame:getTitle(), 'sandbox', 1, true) then			-- did the {{#invoke:}} use sandbox version?
    		cfg = mw.loadData ('Module:Citation/CS1/Configuration/sandbox');		-- load sandbox versions of Configuration and Whitelist and ...
    		whitelist = mw.loadData ('Module:Citation/CS1/Whitelist/sandbox');
    		validation = require ('Module:Citation/CS1/Date_validation/sandbox');	-- ... sandbox version of date validation code
    
    	else																		-- otherwise
    		cfg = mw.loadData ('Module:Citation/CS1/Configuration');				-- load live versions of Configuration and Whitelist and ...
    		whitelist = mw.loadData ('Module:Citation/CS1/Whitelist');
    		validation = require ('Module:Citation/CS1/Date_validation');			-- ... live version of date validation code
    	end
    
    	dates = validation.dates;													-- imported functions
    	year_date_check = validation.year_date_check;
    
    	local args = {};
    	local suggestions = {};
    	local error_text, error_state;
    
    	local config = {};
    	for k, v in pairs( frame.args ) do
    		config[k] = v;
    		args[k] = v;	   
    	end	
    
    	local capture;																-- the single supported capture when matching unknown parameters using patterns
    	for k, v in pairs( pframe.args ) do
    		if v ~= '' then
    			if not validate( k ) then			
    				error_text = "";
    				if type( k ) ~= 'string' then
    					-- Exclude empty numbered parameters
    					if v:match("%S+") ~= nil then
    						error_text, error_state = set_error( 'text_ignored', {v}, true );
    					end
    				elseif validate( k:lower() ) then 
    					error_text, error_state = set_error( 'parameter_ignored_suggest', {k, k:lower()}, true );
    				else
    					if nil == suggestions.suggestions then						-- if this table is nil then we need to load it
    						if nil ~= string.find (frame:getTitle(), 'sandbox', 1, true) then			-- did the {{#invoke:}} use sandbox version?
    							suggestions = mw.loadData( 'Module:Citation/CS1/Suggestions/sandbox' );	-- use the sandbox version
    						else
    							suggestions = mw.loadData( 'Module:Citation/CS1/Suggestions' );			-- use the live version
    						end
    					end
    					for pattern, param in pairs (suggestions.patterns) do		-- loop through the patterns to see if we can suggest a proper parameter
    						capture = k:match (pattern);							-- the whole match if no caputre in pattern else the capture if a match
    						if capture then											-- if the pattern matches 
    							param = substitute( param, capture );				-- add the capture to the suggested parameter (typically the enumerator)
    							error_text, error_state = set_error( 'parameter_ignored_suggest', {k, param}, true );	-- set the error message
    						end
    					end
    					if not is_set (error_text) then								-- couldn't match with a pattern, is there an expicit suggestion?
    						if suggestions.suggestions[ k:lower() ] ~= nil then
    							error_text, error_state = set_error( 'parameter_ignored_suggest', {k, suggestions.suggestions[ k:lower() ]}, true );
    						else
    							error_text, error_state = set_error( 'parameter_ignored', {k}, true );
    						end
    					end
    				end				  
    				if error_text ~= '' then
    					table.insert( z.message_tail, {error_text, error_state} );
    				end				
    			end
    			args[k] = v;
    		elseif args[k] ~= nil or (k == 'postscript') then
    			args[k] = v;
    		end		
    	end	
    
    	for k, v in pairs( args ) do
    		if 'string' == type (k) then											-- don't evaluate positional parameters
    			has_invisible_chars (k, v);
    		end
    	end
    	return citation0( config, args)
    end
    
    return z