Module:Citation/CS1

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

local z = {
    error_categories = {};
    error_ids = {};
    message_tail = {};
}

-- Include translation message hooks, ID and error handling configuration settings.
-- Note that require has tested to be significantly faster than loadData for this 
-- usage.  This might be a side effect of the unnecessary cloning described 
-- in bugzilla 47300.
local cfg = require( 'Module:Citation/CS1/Configuration' );

-- Contains a list of all recognized parameters
local whitelist = mw.loadData( 'Module:Citation/CS1/Whitelist' );

-- Whether variable is set or not
function is_set( var )
    return not (var == nil or var == '');
end

-- First set variable or nil if none
function first_set(...)
    local list = {...};
    for _, var in pairs(list) do
        if is_set( var ) then
            return var;
        end
    end
end

-- Whether needle is in haystack
function inArray( 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

-- Populates numbered arguments in a message string using an argument table.
function substitute( msg, args )
    return args and tostring( mw.message.newRawMessage( msg, args ) ) or msg;
end

-- Wraps a string using a message_list configuration taking one argument
function wrap( key, str )
    if not is_set( str ) then
        return "";
    elseif inArray( key, { 'italic-title', 'trans-italic-title' } ) then
        str = safeforitalics( str );
    end
    return substitute( cfg.messages[key], {str} );
end

--[[
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.
]]
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 list == nil then
                error( cfg.messages['unknown_argument_map'] );
            elseif type( list ) == 'string' then
                v, origin[k] = args[list], list;
            else
                v, origin[k] = selectone( args, list, 'redundant_parameters' );
                if origin[k] == nil then
                    origin[k] = '';   --Empty string, not nil;
                end
            end
            
            if v == nil then
                v = cfg.defaults[k] or "";
                origin[k] = '';   --Empty string, not nil;
            end
            
            tbl = rawset( tbl, k, v );
            return v;
        end,
    });
end

-- Checks that parameter name is valid using the whitelist
function validate( name )
    name = tostring( name );
    
    -- Normal arguments
    if whitelist.basic_arguments[ name ] then
        return true;
    end
    
    -- Arguments with numbers in them
    name = name:gsub( "%d+", "#" );
    if whitelist.numbered_arguments[ name ] then
        return true;
    end
    
    -- Not found, argument not supported.
    return false
end

-- Formats a comment for error trapping
function errorcomment( content, hidden )
    return wrap( hidden and 'hidden-error' or 'visible-error', content );
end

--[[
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.
]]
function seterror( 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 inArray( 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 errorcomment( message, error_state.hidden );
end

-- Formats a wiki style external link
function externallinkid(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 " ",
        options.prefix, url_string, options.suffix or "",
        mw.text.nowiki(options.id)
    );
end

-- Formats a wiki style internal link
function internallinkid(options)
    return mw.ustring.format( '[[%s|%s]]%s[[%s%s%s|%s]]',
        options.link, options.label, options.separator or " ",
        options.prefix, options.id, options.suffix or "",
        mw.text.nowiki(options.id)
    );
end

-- Format an external link with error checking
function externallink( URL, label, source )
    local error_str = "";
    if not is_set( label ) then
        label = URL;
        if is_set( source ) then
            error_str = seterror( 'bare_url_missing_title', { wrap( 'parameter', source ) }, false, " " );
        else
            error( cfg.messages["bare_url_no_origin"] );
        end            
    end
    if not checkurl( URL ) then
        error_str = seterror( 'bad_url', {}, false, " " ) .. error_str;
    end
    return table.concat({ "[", URL, " ", safeforurl( label ), "]", error_str });
end

-- Formats a link to Amazon
function amazon(id, domain)
    if not is_set(domain) then 
        domain = "com"
    elseif ( "jp" == domain or "uk" == domain ) then
        domain = "co." .. domain
    end
    local handler = cfg.id_handlers['ASIN'];
    return externallinkid({link = handler.link,
        label=handler.label , prefix="//www.amazon."..domain.."/dp/",id=id,
        encode=handler.encode, separator = handler.separator})
end

-- Formats a DOI and checks for DOI errors.
function doi(id, inactive)
    local cat = ""
    local handler = cfg.id_handlers['DOI'];
    
    local text;
    if is_set(inactive) then
        text = "[[" .. handler.link .. "|" .. handler.label .. "]]:" .. id;
        table.insert( z.error_categories, "Pages with DOIs inactive since " .. selectyear(inactive) );        
        inactive = " (" .. cfg.messages['inactive'] .. " " .. inactive .. ")" 
    else 
        text = externallinkid({link = handler.link, label = handler.label,
            prefix=handler.prefix,id=id,separator=handler.separator, encode=handler.encode})
        inactive = "" 
    end
    if ( string.sub(id,1,3) ~= "10." ) then      
        cat = seterror( 'bad_doi' );
    end
    return text .. inactive .. cat 
end

-- Formats an OpenLibrary link, and checks for associated errors.
function openlibrary(id)
    local code = id:sub(-1,-1)
    local handler = cfg.id_handlers['OL'];
    if ( code == "A" ) then
        return externallinkid({link=handler.link, label=handler.label,
            prefix="http://openlibrary.org/authors/OL",id=id, separator=handler.separator,
            encode = handler.encode})
    elseif ( code == "M" ) then
        return externallinkid({link=handler.link, label=handler.label,
            prefix="http://openlibrary.org/books/OL",id=id, separator=handler.separator,
            encode = handler.encode})
    elseif ( code == "W" ) then
        return externallinkid({link=handler.link, label=handler.label,
            prefix= "http://openlibrary.org/works/OL",id=id, separator=handler.separator,
            encode = handler.encode})
    else
        return externallinkid({link=handler.link, label=handler.label,
            prefix= "http://openlibrary.org/OL",id=id, separator=handler.separator,
            encode = handler.encode}) .. 
            ' ' .. seterror( 'bad_ol' );
    end
end

--[[
Determines whether an URL string is valid

At present the only check is whether the string appears to 
be prefixed with a URI scheme.  It is not determined whether 
the URI scheme is valid or whether the URL is otherwise well 
formed.
]]
function checkurl( url_str )
    -- Protocol-relative or URL scheme
    return url_str:sub(1,2) == "//" or url_str:match( "^[^/]*:" ) ~= nil;
end

-- Removes irrelevant text and dashes from ISBN number
-- Similar to that used for Special:BookSources
function cleanisbn( isbn_str )
    return isbn_str:gsub( "[^-0-9X]", "" );
end

-- Determines whether an ISBN string is valid
function checkisbn( isbn_str )
    isbn_str = cleanisbn( isbn_str ):gsub( "-", "" );
    local len = isbn_str:len();
 
    if len ~= 10 and len ~= 13 then
        return false;
    end
 
    local temp = 0;
    if len == 10 then
        if isbn_str:match( "^%d*X?$" ) == nil then return false; end
        isbn_str = { isbn_str:byte(1, len) };
        for i, v in ipairs( isbn_str ) do
            if v == string.byte( "X" ) then
                temp = temp + 10*( 11 - i );
            else
                temp = temp + tonumber( string.char(v) )*(11-i);
            end
        end
        return temp % 11 == 0;
    else
        if isbn_str:match( "^%d*$" ) == nil then return false; end
        isbn_str = { isbn_str:byte(1, len) };
        for i, v in ipairs( isbn_str ) do
            temp = temp + (3 - 2*(i % 2)) * tonumber( string.char(v) );
        end
        return temp % 10 == 0;
    end
end

-- Gets the display text for a wikilink like [[A|B]] or [[B]] gives B
function removewikilink( str )
    return (str:gsub( "%[%[([^%[%]]*)%]%]", function(l)
        return l:gsub( "^[^|]*|(.*)$", "%1" ):gsub("^%s*(.-)%s*$", "%1");
    end));
end

-- Escape sequences for content that will be used for URL descriptions
function safeforurl( str )
    if str:match( "%[%[.-%]%]" ) ~= nil then 
        table.insert( z.message_tail, { seterror( 'wikilink_in_url', {}, true ) } );
    end
    
    return str:gsub( '[%[%]\n]', {    
        ['['] = '[',
        [']'] = ']',
        ['\n'] = ' ' } );
end

-- Converts a hyphen to a dash
function hyphentodash( str )
    if not is_set(str) or str:match( "[%[%]{}<>]" ) ~= nil then
        return str;
    end    
    return str:gsub( '-', '–' );
end

-- Protects a string that will be wrapped in wiki italic markup '' ... ''
function safeforitalics( str )
    --[[ Note: We can not 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. ]]
    
    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

--[[
Joins a sequence of strings together while checking for duplicate separation
characters.
]]
function safejoin( 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 = '';
    local comp = '';
    local end_chr = '';
    local trim;
    for _, value in ipairs( tbl ) do
        if value == nil then value = ''; end
        
        if str == '' then
            str = value;
        elseif value ~= '' then
            if value:sub(1,1) == '<' then
                -- Special case of values enclosed in spans and other markup.
                comp = value:gsub( "%b<>", "" );
            else
                comp = value;
            end
            
            if comp:sub(1,1) == duplicate_char then
                trim = false;
                end_chr = str:sub(-1,-1);
                -- str = str .. "<HERE(enchr=" .. end_chr.. ")"
                if end_chr == duplicate_char then
                    str = str:sub(1,-2);
                elseif end_chr == "'" then
                    if str:sub(-3,-1) == duplicate_char .. "''" then
                        str = str:sub(1, -4) .. "''";
                    elseif str:sub(-5,-1) == duplicate_char .. "]]''" then
                        trim = true;
                    elseif str:sub(-4,-1) == duplicate_char .. "]''" then
                        trim = true;
                    end
                elseif end_chr == "]" then
                    if str:sub(-3,-1) == duplicate_char .. "]]" then
                        trim = true;
                    elseif str:sub(-2,-1) == duplicate_char .. "]" then
                        trim = true;
                    end
                elseif end_chr == " " then
                    if str:sub(-2,-1) == duplicate_char .. " " then
                        str = str:sub(1,-3);
                    end
                end

                if trim then
                    if value ~= comp then 
                        local dup2 = duplicate_char;
                        if dup2:match( "%A" ) then dup2 = "%" .. dup2; end
                        
                        value = value:gsub( "(%b<>)" .. dup2, "%1", 1 )
                    else
                        value = value:sub( 2, -1 );
                    end
                end
            end
            str = str .. value;
        end
    end
    return str;
end  

--[[
Return the year portion of a date string, if possible.  
Returns empty string if the argument can not be interpreted
as a year.
]]
function selectyear( str )
    -- Is the input a simple number?
    local num = tonumber( str ); 
    if num ~= nil and num > 0 and num < 2100 and num == math.floor(num) then
        return str;
    else
        -- Use formatDate to interpret more complicated formats
        local lang = mw.getContentLanguage();
        local good, result;
        good, result = pcall( lang.formatDate, lang, 'Y', str )
        if good then 
            return result;
        else
            -- Can't make sense of this input, return blank.
            return "";
        end
    end
end

-- Attempts to convert names to initials.
function reducetoinitials(first)
    local initials = {}
    for word in string.gmatch(first, "%S+") do
        table.insert(initials, string.sub(word,1,1)) -- Vancouver format does not include full stops.
    end
    return table.concat(initials) -- Vancouver format does not include spaces.
end

-- Formats a list of people (e.g. authors / editors) 
function listpeople(control, people)
    local sep = control.sep;
    local namesep = control.namesep
    local format = control.format
    local maximum = control.maximum
    local lastauthoramp = control.lastauthoramp;
    local text = {}
    local etal = false;
    
    if sep:sub(-1,-1) ~= " " then sep = sep .. " " end
    if maximum ~= nil and maximum < 1 then return "", 0; end
    
    for i,person in ipairs(people) do
        if is_set(person.last) then
            local mask = person.mask
            local one
            local sep_one = sep;
            if maximum ~= nil 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 first = reducetoinitials(first) end
                    one = one .. namesep .. first 
                end
                if is_set(person.link) then one = "[[" .. person.link .. "|" .. one .. "]]" end
            end
            table.insert( text, one )
            table.insert( text, sep_one )
        end
    end

    local count = #text / 2;
    if count > 0 then 
        if count > 1 and is_set(lastauthoramp) and not etal then
            text[#text-2] = " & ";
        end
        text[#text] = nil; 
    end
    
    local result = table.concat(text) -- construct list
    if etal then 
        local etal_text = cfg.messages['et al'];
        result = result .. " " .. etal_text;
    end
    
    -- if necessary wrap result in <span> tag to format in Small Caps
    if ( "scap" == format ) then result = 
        '<span class="smallcaps" style="font-variant:small-caps">' .. result .. '</span>';
    end 
    return result, count
end

-- Generates a CITEREF anchor ID.
function anchorid( options )
    return "CITEREF" .. table.concat( options );
end

-- Gets name list from the input arguments
function extractnames(args, list_name)
    local names = {};
    local i = 1;
    local last;
    
    while true do
        last = selectone( args, cfg.aliases[list_name .. '-Last'], 'redundant_parameters', i );
        if not is_set(last) then
            -- just in case someone passed in an empty parameter
            break;
        end
        names[i] = {
            last = last,
            first = selectone( args, cfg.aliases[list_name .. '-First'], 'redundant_parameters', i ),
            link = selectone( args, cfg.aliases[list_name .. '-Link'], 'redundant_parameters', i ),
            mask = selectone( args, cfg.aliases[list_name .. '-Mask'], 'redundant_parameters', i )
        };
        i = i + 1;
    end
    return names;
end

-- Populates ID table from arguments using configuration settings
function extractids( args )
    local id_list = {};
    for k, v in pairs( cfg.id_handlers ) do    
        v = selectone( args, v.parameters, 'redundant_parameters' );
        if is_set(v) then id_list[k] = v; end
    end
    return id_list;
end

-- Takes a table of IDs and turns it into a table of formatted ID outputs.
function buildidlist( 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
        -- fallback to read-only cfg
        handler = setmetatable( { ['id'] = v }, fallback(k) );
        
        if handler.mode == 'external' then
            table.insert( new_list, {handler.label, externallinkid( handler ) } );
        elseif handler.mode == 'internal' then
            table.insert( new_list, {handler.label, internallinkid( 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 == 'ASIN' then
            table.insert( new_list, {handler.label, amazon( v, options.ASINTLD ) } ); 
        elseif k == 'OL' then
            table.insert( new_list, {handler.label, openlibrary( v ) } );
        elseif k == 'ISBN' then
            local ISBN = internallinkid( handler );
            if not checkisbn( v ) and not is_set(options.IgnoreISBN) then
                ISBN = ISBN .. seterror( 'bad_isbn', {}, false, " ", "" );
            end
            table.insert( new_list, {handler.label, ISBN } );                
        else
            error( cfg.messages['unknown_manual_ID'] );
        end
    end
    
    function comp( a, b )
        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
  
-- Chooses one matching parameter from a list of parameters to consider
-- Generates an error if more than one match is present.
function selectone( args, possible, error_condition, index )
    local value = nil;
    local selected = '';
    local error_list = {};
    
    if index ~= nil then index = tostring(index); end
    
    -- Handle special case of "#" replaced by empty string
    if index == '1' then
        for _, v in ipairs( possible ) do
            v = v:gsub( "#", "" );
            if is_set(args[v]) then
                if value ~= nil and selected ~= v then
                    table.insert( error_list, v );
                else
                    value = args[v];
                    selected = v;
                end
            end
        end        
    end
    
    for _, v in ipairs( possible ) do
        if index ~= nil then
            v = v:gsub( "#", index );
        end
        if is_set(args[v]) then
            if value ~= nil and selected ~=  v then
                table.insert( error_list, v );
            else
                value = args[v];
                selected = v;
            end
        end
    end
    
    if #error_list > 0 then
        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( '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( 'parameter', selected );
        table.insert( z.message_tail, { seterror( error_condition, {error_str}, true ) } );
    end
    
    return value, selected;
end

-- COinS metadata (see <http://ocoins.info/>) allows automated tools to parse
-- the citation information.
function COinS(data)
    if 'table' ~= type(data) or nil == next(data) then
        return '';
    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( removewikilink( value ) ) } );
            end
        end
    });
    
    if is_set(data.Chapter) then
        OCinSoutput.rft_val_fmt = "info:ofi/fmt:kev:mtx:book";
        OCinSoutput["rft.genre"] = "bookitem";
        OCinSoutput["rft.btitle"] = data.Chapter;
        OCinSoutput["rft.atitle"] = data.Title;
    elseif is_set(data.Periodical) then
        OCinSoutput.rft_val_fmt = "info:ofi/fmt:kev:mtx:journal";
        OCinSoutput["rft.genre"] = "article";
        OCinSoutput["rft.jtitle"] = data.Periodical;
        OCinSoutput["rft.atitle"] = data.Title;
    else
        OCinSoutput.rft_val_fmt = "info:ofi/fmt:kev:mtx:book";
        OCinSoutput["rft.genre"] = "book"
        OCinSoutput["rft.btitle"] = data.Title;
    end
    
    OCinSoutput["rft.place"] = data.PublicationPlace;
    OCinSoutput["rft.date"] = data.Date;
    OCinSoutput["rft.series"] = data.Series;
    OCinSoutput["rft.volume"] = data.Volume;
    OCinSoutput["rft.issue"] = data.Issue;
    OCinSoutput["rft.pages"] = data.Pages;
    OCinSoutput["rft.edition"] = data.Edition;
    OCinSoutput["rft.pub"] = data.PublisherName;
    
    for k, v in pairs( data.ID_list ) do
        local id, value = cfg.id_handlers[k].COinS;
        if k == 'ISBN' then value = cleanisbn( 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 = v.last, v.first;
        if k == 1 then
            if is_set(last) then
                OCinSoutput["rft.aulast"] = last;
            end
            if is_set(first) then 
                OCinSoutput["rft.aufirst"] = first;
            end
        end
        if is_set(last) and is_set(first) then
            OCinSoutput["rft.au"] = table.concat{ last, ", ", first };
        elseif is_set(last) then
            OCinSoutput["rft.au"] = last;
        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

--[[
This is the main function foing the majority of the citation
formatting.
]]
function citation0( config, args)
    --[[ 
    Load Input Parameters
    The argment_wrapper facillitates the mapping of multiple
    aliases to single internal variable.
    ]]
    local A = argument_wrapper( args );

    local i 
    local PPrefix = A['PPrefix']
    local PPPrefix = A['PPPrefix']
    if is_set( A['NoPP'] ) then PPPrefix = "" PPrefix = "" end
    
    -- Pick out the relevant fields from the arguments.  Different citation templates
    -- define different field names for the same underlying things.    
    local Authors = A['Authors'];
    local a = extractnames( args, 'AuthorList' );

    local Coauthors = A['Coauthors'];
    local Others = A['Others'];
    local Editors = A['Editors'];
    local e = extractnames( args, 'EditorList' );

    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 BookTitle = A['BookTitle'];
    local Conference = A['Conference'];
    local TransTitle = A['TransTitle'];
    local TitleNote = A['TitleNote'];
    local TitleLink = A['TitleLink'];
    local Chapter = A['Chapter'];
    local ChapterLink = A['ChapterLink'];
    local TransChapter = A['TransChapter'];
    local TitleType = A['TitleType'];
    local ArchiveURL = A['ArchiveURL'];
    local URL = A['URL']
    local URLorigin = A:ORIGIN('URL');
    local ChapterURL = A['ChapterURL'];
    local ChapterURLorigin = A:ORIGIN('ChapterURL');
    local ConferenceURL = A['ConferenceURL'];
    local ConferenceURLorigin = A:ORIGIN('ConferenceURL');
    local Periodical = A['Periodical'];
    
    if ( config.CitationClass == "encyclopaedia" ) then
        if not is_set(Chapter) then
            if not is_set(Title) then
                Title = Periodical;
                Periodical = '';
            else
                Chapter = Title
                TransChapter = TransTitle
                Title = '';
                TransTitle = '';
            end
        end
    end

    local Series = A['Series'];
    local Volume = A['Volume'];
    local Issue = A['Issue'];
    local Position = '';
    local Page, Pages, At, page_type;
    
    Page = A['Page'];
    Pages = hyphentodash( A['Pages'] );
    At = A['At'];
    
    if is_set(Page) then
        if is_set(Pages) or is_set(At) then
            Page = Page .. " " .. seterror('extra_pages');
            Pages = '';
            At = '';
        end
    elseif is_set(Pages) then
        if is_set(At) then
            Pages = Pages .. " " .. seterror('extra_pages');
            At = '';
        end
    end    
    
    local Edition = A['Edition'];
    local PublicationPlace = A['PublicationPlace']
    local Place = A['Place'];
    
    if not is_set(PublicationPlace) and is_set(Place) then
        PublicationPlace = Place;
    end
    
    if PublicationPlace == Place then Place = ''; end
    
    local PublisherName = A['PublisherName'];
    local SubscriptionRequired = A['SubscriptionRequired'];
    local Via = A['Via'];
    local AccessDate = A['AccessDate'];
    local ArchiveDate = A['ArchiveDate'];
    local Agency = A['Agency'];
    local DeadURL = A['DeadURL']
    local Language = A['Language'];
    local Format = A['Format'];
    local Ref = A['Ref'];
    
    local DoiBroken = A['DoiBroken'];
    local ID = A['ID'];
    local ASINTLD = A['ASINTLD'];
    local IgnoreISBN = A['IgnoreISBN'];

    local ID_list = extractids( args );
    
    local Quote = A['Quote'];
    local PostScript = A['PostScript'];
    local LayURL = A['LayURL'];
    local LaySource = A['LaySource'];
    local Transcript = A['Transcript'];
    local TranscriptURL = A['TranscriptURL'] 
    local TranscriptURLorigin = A:ORIGIN('TranscriptURL');
    local sepc = A['Separator'];
    local LastAuthorAmp = A['LastAuthorAmp'];
    local no_tracking_cats = A['NoTracking'];

    local this_page = mw.title.getCurrentTitle();  --Also used for COinS
    
    if not is_set(no_tracking_cats) then
        for k, v in pairs( cfg.uncategorized_namespaces ) do
            if this_page.nsText == v then
                no_tracking_cats = "true";
                break;
            end
        end
    end

    if ( config.CitationClass == "journal" ) then
        if not is_set(URL) and is_set(ID_list['PMC']) then
            local Embargo = A['Embargo'];
            if is_set(Embargo) then
                local lang = mw.getContentLanguage();
                local good1, result1, good2, result2;
                good1, result1 = pcall( lang.formatDate, lang, 'U', Embargo );
                good2, result2 = pcall( lang.formatDate, lang, 'U' );
                
                if good1 and good2 and tonumber( result1 ) < tonumber( result2 ) then 
                    URL = "http://www.ncbi.nlm.nih.gov/pmc/articles/PMC" .. ID_list['PMC'];
                    URLorigin = cfg.id_handlers['PMC'].parameters[1];
                end
            else
                URL = "http://www.ncbi.nlm.nih.gov/pmc/articles/PMC" .. ID_list['PMC'];
                URLorigin = cfg.id_handlers['PMC'].parameters[1];
            end
        end
    end

    -- At this point fields may be nil if they weren't specified in the template use.  We can use that fact.
    
    -- Account for the oddity that is {{cite conference}}, before generation of COinS data.
    if is_set(BookTitle) then
        Chapter = Title;
        ChapterLink = TitleLink;
        TransChapter = TransTitle;
        Title = BookTitle;
        TitleLink = '';
        TransTitle = '';
    end
    -- Account for the oddity that is {{cite episode}}, before generation of COinS data.
    if config.CitationClass == "episode" then
        local AirDate = A['AirDate'];
        local SeriesLink = A['SeriesLink'];
        local Season = A['Season'];
        local SeriesNumber = A['SeriesNumber'];
        local Network = A['Network'];
        local Station = A['Station'];
        local s, n = {}, {};
        local Sep = (first_set(A["SeriesSeparator"], A["Separator"]) or "") .. " ";
        
        if is_set(Issue) then table.insert(s, cfg.messages["episode"] .. " " .. Issue); Issue = ''; end
        if is_set(Season) then table.insert(s, cfg.messages["season"] .. " " .. Season); end
        if is_set(SeriesNumber) then table.insert(s, cfg.messages["series"] .. " " .. SeriesNumber); end
        if is_set(Network) then table.insert(n, Network); end
        if is_set(Station) then table.insert(n, Station); end
        
        Date = Date or AirDate;
        Chapter = Title;
        ChapterLink = TitleLink;
        TransChapter = TransTitle;
        Title = Series;
        TitleLink = SeriesLink;
        TransTitle = '';
        
        Series = table.concat(s, Sep);
        ID = table.concat(n, Sep);
    end
    
    -- COinS metadata (see <http://ocoins.info/>) for
    -- automated parsing of citation information.
    local OCinSoutput = COinS{
        ['Periodical'] = Periodical,
        ['Chapter'] = Chapter,
        ['Title'] = Title,
        ['PublicationPlace'] = PublicationPlace,
        ['Date'] = first_set(Date, Year, PublicationDate),
        ['Series'] = Series,
        ['Volume'] = Volume,
        ['Issue'] = Issue,
        ['Pages'] = first_set(Page, Pages, At),
        ['Edition'] = Edition,
        ['PublisherName'] = PublisherName,
        ['URL'] = first_set( URL, ChapterURL ),
        ['Authors'] = a,
        ['ID_list'] = ID_list,
        ['RawPage'] = this_page.prefixedText,
    };

    if is_set(Periodical) and not is_set(Chapter) and is_set(Title) then
        Chapter = Title;
        ChapterLink = TitleLink;
        TransChapter = TransTitle;
        Title = '';
        TitleLink = '';
        TransTitle = '';
    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.
    if not is_set(Authors) then
        local Maximum = tonumber( A['DisplayAuthors'] );
        
        -- Preserve old-style implicit et al.
        if not is_set(Maximum) and #a == 9 then 
            Maximum = 8;
            table.insert( z.message_tail, { seterror('implict_etal_author', {}, true ) } );
        elseif not is_set(Maximum) then
            Maximum = #a + 1;
        end
            
        local control = { 
            sep = A["AuthorSeparator"] .. " ",
            namesep = (first_set(A["AuthorNameSeparator"], A["NameSeparator"]) or "") .. " ",
            format = A["AuthorFormat"],
            maximum = Maximum,
            lastauthoramp = LastAuthorAmp
        };
        
        -- If the coauthor field is also used, prevent ampersand and et al. formatting.
        if is_set(Coauthors) then
            control.lastauthoramp = nil;
            control.maximum = #a + 1;
        end
        
        Authors = listpeople(control, a) 
    end
    
    local EditorCount
    if not is_set(Editors) then
        local Maximum = tonumber( A['DisplayEditors'] );
        -- Preserve old-style implicit et al.
        if not is_set(Maximum) and #e == 4 then 
            Maximum = 3;
            table.insert( z.message_tail, { seterror('implict_etal_editor', {}, true) } );
        elseif not is_set(Maximum) then
            Maximum = #e + 1;
        end

        local control = { 
            sep = A["EditorSeparator"] .. " ",
            namesep = (first_set(A["EditorNameSeparator"], A["NameSeparator"]) or "") .. " ",
            format = A['EditorFormat'],
            maximum = Maximum,
            lastauthoramp = LastAuthorAmp
        };

        Editors, EditorCount = listpeople(control, e);
    else
        EditorCount = 1;
    end
    
    if not is_set(Date) then
        Date = Year;
        if is_set(Date) then
            local Month = A['Month'];
            if is_set(Month) then 
                Date = Month .. " " .. Date;
                local Day = A['Day']
                if is_set(Day) then Date = Day .. " " .. Date end
            end
        end
    end
    
    if inArray(PublicationDate, {Date, Year}) then PublicationDate = ''; end
    if not is_set(Date) and is_set(PublicationDate) then
        Date = PublicationDate;
        PublicationDate = '';
    end

    -- Captures the value for Date prior to adding parens or other textual transformations
    local DateIn = Date;
    
    if  not is_set(URL) and
        not is_set(ChapterURL) and
        not is_set(ArchiveURL) and
        not is_set(ConferenceURL) and
        not is_set(TranscriptURL) then
        
        -- Test if cite web is called without giving a URL
        if ( config.CitationClass == "web" ) then
            table.insert( z.message_tail, { seterror( 'cite_web_url', {}, true ) } );
        end
        
        -- Test if accessdate is given without giving a URL
        if is_set(AccessDate) then
            table.insert( z.message_tail, { seterror( 'accessdate_missing_url', {}, true ) } );
            AccessDate = '';
        end
        
        -- Test if format is given without giving a URL
        if is_set(Format) then
            Format = Format .. seterror( 'format_missing_url' );
        end
    end
    
    -- Test if citation has no title
    if  not is_set(Chapter) and
        not is_set(Title) and
        not is_set(Periodical) and
        not is_set(Conference) and
        not is_set(TransTitle) and
        not is_set(TransChapter) then
        table.insert( z.message_tail, { seterror( 'citation_missing_title', {}, true ) } );
    end
    
    Format = is_set(Format) and " (" .. Format .. ")" or "";
    
    local OriginalURL = URL
    DeadURL = DeadURL:lower();
    if is_set( ArchiveURL ) then
        if ( DeadURL ~= "no" ) then
            URL = ArchiveURL
            URLorigin = A:ORIGIN('ArchiveURL')
        end
    end
    
    -- Format chapter / article title
    if is_set(Chapter) and is_set(ChapterLink) then 
        Chapter = "[[" .. ChapterLink .. "|" .. Chapter .. "]]";
    end
    if is_set(Periodical) and is_set(Title) then
        Chapter = wrap( 'italic-title', Chapter );
        TransChapter = wrap( 'trans-italic-title', TransChapter );
    else
        Chapter = wrap( 'quoted-title', Chapter );
        TransChapter = wrap( 'trans-quoted-title', TransChapter );
    end
    
    local TransError = ""
    if is_set(TransChapter) then
        if not is_set(Chapter) then
            TransError = " " .. seterror( 'trans_missing_chapter' );
        else
            TransChapter = " " .. TransChapter;
        end
    end
    
    Chapter = Chapter .. TransChapter;
    
    if is_set(Chapter) then
        if not is_set(ChapterLink) then
            if is_set(ChapterURL) then
                Chapter = externallink( ChapterURL, Chapter ) .. TransError;
                if not is_set(URL) then
                    Chapter = Chapter .. Format;
                    Format = "";
                end
            elseif is_set(URL) then 
                Chapter = externallink( URL, Chapter ) .. TransError .. Format;
                URL = "";
                Format = "";
            else
                Chapter = Chapter .. TransError;
            end            
        elseif is_set(ChapterURL) then
            Chapter = Chapter .. " " .. externallink( ChapterURL, nil, ChapterURLorigin ) .. 
                TransError;
        else
            Chapter = Chapter .. TransError;
        end
        Chapter = Chapter .. sepc .. " " -- with end-space
    elseif is_set(ChapterURL) then
        Chapter = " " .. externallink( ChapterURL, nil, ChapterURLorigin ) .. sepc .. " ";
    end        
    
    -- Format main title.
    if is_set(TitleLink) and is_set(Title) then
        Title = "[[" .. TitleLink .. "|" .. Title .. "]]"
    end
    
    if is_set(Periodical) then
        Title = wrap( 'quoted-title', Title );
        TransTitle = wrap( 'trans-quoted-title', TransTitle );
    elseif inArray(config.CitationClass, {"web","news","pressrelease"}) and
            not is_set(Chapter) then
        Title = wrap( 'quoted-title', Title );
        TransTitle = wrap( 'trans-quoted-title', TransTitle );
    else
        Title = wrap( 'italic-title', Title );
        TransTitle = wrap( 'trans-italic-title', TransTitle );
    end
    
    TransError = "";
    if is_set(TransTitle) then
        if not is_set(Title) then
            TransError = " " .. seterror( 'trans_missing_title' );
        else
            TransTitle = " " .. TransTitle;
        end
    end
    
    Title = Title .. TransTitle;
    
    if is_set(Title) then
        if not is_set(TitleLink) and is_set(URL) then 
            Title = externallink( URL, Title ) .. TransError .. Format       
            URL = "";
            Format = "";
        else
            Title = Title .. TransError;
        end
    end
    
    if is_set(Place) then
        if sepc == '.' then
            Place = " " .. wrap( 'written', Place ) .. sepc .. " ";
        else
            Place = " " .. substitute( cfg.messages['written']:lower(), {Place} ) .. sepc .. " ";
        end
    end
    
    if is_set(Conference) then
        if is_set(ConferenceURL) then
            Conference = externallink( ConferenceURL, Conference );
        end
        Conference = " " .. Conference
    elseif is_set(ConferenceURL) then
        Conference = " " .. externallink( ConferenceURL, nil, ConferenceURLorigin );
    end
    
    if not is_set(Position) then
        local Minutes = A['Minutes'];
        if is_set(Minutes) then
            Position = " " .. Minutes .. " " .. cfg.messages['minutes'];
        else
            local Time = A['Time'];
            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
    
    if not is_set(Page) then
        if is_set(Pages) then
            if is_set(Periodical) and
                not inArray(config.CitationClass, {"encyclopaedia","web","book","news"}) then
                Pages = ": " .. Pages;
            elseif tonumber(Pages) ~= nil then
                Pages = sepc .." " .. PPrefix .. Pages;
            else
                Pages = sepc .." " .. PPPrefix .. Pages;
            end
        end
    else
        if is_set(Periodical) and
            not inArray(config.CitationClass, {"encyclopaedia","web","book","news"}) then
            Page = ": " .. Page;
        else
            Page = sepc .." " .. PPrefix .. Page;
        end
    end
    
    At = is_set(At) and (sepc .. " " .. At) or "";
    Others = is_set(Others) and (sepc .. " " .. Others) or "";
    TitleType = is_set(TitleType) and (" (" .. TitleType .. ")") or "";
    TitleNote = is_set(TitleNote) and (sepc .. " " .. TitleNote) or "";
    Language = is_set(Language) and (" " .. wrap( 'language', Language )) or "";
    Edition = is_set(Edition) and (" " .. wrap( 'edition', Edition )) or "";
    Issue = is_set(Issue) and (" (" .. Issue .. ")") or "";
    Series = is_set(Series) and (sepc .. " " .. Series) or "";
    OrigYear = is_set(OrigYear) and (" [" .. OrigYear .. "]") or "";
    Agency = is_set(Agency) and (sepc .. " " .. Agency) or "";
    
    if is_set(Volume) then
        if ( mw.ustring.len(Volume) > 4 )
          then Volume = sepc .." " .. Volume;
          else Volume = " <b>" .. hyphentodash(Volume) .. "</b>";
        end
    end
    
    ------------------------------------ totally unrelated data
    if is_set(Via) then Via = " " .. wrap( 'via', Via ); end
    if is_set(AccessDate) then
        local retrv_text = " " .. cfg.messages['retrieved']
        if (sepc ~= ".") then retrv_text = retrv_text:lower() end
        AccessDate = '<span class="reference-accessdate">' .. sepc
            .. substitute( retrv_text, {AccessDate} ) .. '</span>'
    end
    
    if is_set(SubscriptionRequired) then
        SubscriptionRequired = sepc .. " " .. cfg.messages['subscription'];
    end
    
    if is_set(ID) then ID = sepc .." ".. ID; end
    
    ID_list = buildidlist( ID_list, {DoiBroken = DoiBroken, ASINTLD = ASINTLD, IgnoreISBN = IgnoreISBN} );

    if is_set(URL) then
        URL = " " .. externallink( URL, nil, URLorigin );
    end

    if is_set(Quote) then
        if Quote:sub(1,1) == '"' and Quote:sub(-1,-1) == '"' then
            Quote = Quote:sub(2,-2);
        end
        Quote = sepc .." " .. wrap( 'quoted-text', Quote ); 
        PostScript = "";
    elseif PostScript:lower() == "none" then
        PostScript = "";
    end
    
    local Archived
    if is_set(ArchiveURL) then
        if not is_set(ArchiveDate) then
            ArchiveDate = seterror('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'],
                { externallink( ArchiveURL, arch_text ), ArchiveDate } );
            if not is_set(OriginalURL) then
                Archived = Archived .. " " .. seterror('archive_missing_url');                               
            end
        elseif is_set(OriginalURL) then
            local arch_text = cfg.messages['archived-dead'];
            if sepc ~= "." then arch_text = arch_text:lower() end
            Archived = sepc .. " " .. substitute( arch_text,
                { externallink( OriginalURL, cfg.messages['original'] ), ArchiveDate } );
        else
            local arch_text = cfg.messages['archived-missing'];
            if sepc ~= "." then arch_text = arch_text:lower() end
            Archived = sepc .. " " .. substitute( arch_text, 
                { seterror('archive_missing_url'), ArchiveDate } );
        end
    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; ''" .. safeforitalics(LaySource) .. "''";
        else
            LaySource = "";
        end
        if sepc == '.' then
            Lay = sepc .. " " .. externallink( LayURL, cfg.messages['lay summary'] ) .. LaySource .. LayDate
        else
            Lay = sepc .. " " .. externallink( LayURL, cfg.messages['lay summary']:lower() ) .. LaySource .. LayDate
        end            
    else
        Lay = "";
    end
    
    if is_set(Transcript) then
        if is_set(TranscriptURL) then Transcript = externallink( TranscriptURL, Transcript ); end
    elseif is_set(TranscriptURL) then
        Transcript = externallink( TranscriptURL, nil, TranscriptURLorigin );
    end
    
    local Publisher;
    if is_set(Periodical) and
        not inArray(config.CitationClass, {"encyclopaedia","web","pressrelease"}) 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( 'published', PublicationDate );
            else
                Publisher = PublicationDate;
            end
        end
        if is_set(Publisher) then
            Publisher = " (" .. Publisher .. ")";
        end
    else
        if is_set(PublicationDate) then
            PublicationDate = " (" .. wrap( '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( 'italic-title', Periodical ) 
        else 
            Periodical = wrap( 'italic-title', Periodical )
        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
    if inArray(config.CitationClass, {"journal","citation"}) and is_set(Periodical) then
        if is_set(Others) then Others = Others .. sepc .. " " end
        tcommon = safejoin( {Others, Title, TitleNote, Conference, Periodical, Format, TitleType, Series, 
            Language, Edition, Publisher, Agency, Volume, Issue, Position}, sepc );
    else 
        tcommon = safejoin( {Title, TitleNote, Conference, Periodical, Format, TitleType, Series, Language, 
            Volume, Issue, Others, Edition, Publisher, Agency, Position}, sepc );
    end
    
    if #ID_list > 0 then
        ID_list = safejoin( { sepc .. " ",  table.concat( ID_list, sepc .. " " ), ID }, sepc );
    else
        ID_list = ID;
    end
    
    local idcommon = safejoin( { ID_list, URL, Archived, AccessDate, Via, SubscriptionRequired, Lay, Quote }, sepc );
    local text;
    local pgtext = Page .. Pages .. At;
    
    if is_set(Authors) then
        if is_set(Coauthors) then
            Authors = Authors .. A['AuthorSeparator'] .. " " .. Coauthors
        end
        if is_set(Date) then
            Date = " ("..Date..")" .. OrigYear .. sepc .. " "
        elseif string.sub(Authors,-1,-1) == sepc then
            Authors = Authors .. " "
        else
            Authors = Authors .. sepc .. " "
        end
        if is_set(Editors) then
            local in_text = " " .. cfg.messages['in'] .. " "
            if (sepc ~= '.') then in_text = in_text:lower() end
            if (string.sub(Editors,-1,-1) == sepc)
                then Editors = in_text .. Editors .. " "
                else Editors = in_text .. Editors .. sepc .. " "
            end
        end
        text = safejoin( {Authors, Date, Chapter, Place, Editors, tcommon }, sepc );
        text = safejoin( {text, pgtext, idcommon}, sepc );
    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
            Date = " (" .. Date ..")" .. OrigYear .. sepc .. " "
        else
            if EditorCount <= 1 then
                Editors = Editors .. " (" .. cfg.messages['editor'] .. ")" .. sepc .. " "
            else
                Editors = Editors .. " (" .. cfg.messages['editors'] .. ")" .. sepc .. " "
            end
        end
        text = safejoin( {Editors, Date, Chapter, Place, tcommon}, sepc );
        text = safejoin( {text, pgtext, idcommon}, sepc );
    else
        if is_set(Date) then
            if ( string.sub(tcommon,-1,-1) ~= sepc )
              then Date = sepc .." " .. Date .. OrigYear
              else Date = " " .. Date .. OrigYear
            end
        end
        if config.CitationClass=="journal" and is_set(Periodical) then
            text = safejoin( {Chapter, Place, tcommon}, sepc );
            text = safejoin( {text, pgtext, Date, idcommon}, sepc );
        else
            text = safejoin( {Chapter, Place, tcommon, Date}, sepc );
            text = safejoin( {text, pgtext, idcommon}, sepc );
        end
    end
    
    if is_set(PostScript) and PostScript ~= sepc then
        text = safejoin( {text, sepc}, sepc );  --Deals with italics, spaces, etc.
        text = text:sub(1,-2); --Remove final seperator    
    end    
    
    text = safejoin( {text, PostScript}, sepc );

    -- Now enclose the whole thing in a <span/> element
    if not is_set(Year) then
        if is_set(DateIn) then
            Year = selectyear( DateIn );
        elseif is_set(PublicationDate) then
            Year = selectyear( PublicationDate );
        end
    end
    
    local options = {};
    
    if is_set(config.CitationClass) and config.CitationClass ~= "citation" then
        options.class = "citation " .. config.CitationClass;
    else
        options.class = "citation";
    end
    
    if is_set(Ref) and Ref:lower() ~= "none" then
        local id = Ref
        if ( "harv" == Ref ) then
            local names = {} --table of last names & year
            if is_set(Authors) then
                for i,v in ipairs(a) do 
                    names[i] = v.last 
                    if i == 4 then break end
                end
            elseif is_set(Editors) then
                for i,v in ipairs(e) do 
                    names[i] = v.last 
                    if i == 4 then break end                
                end
            end
            names[ #names + 1 ] = Year;
            id = anchorid(names)
        end
        options.id = id;
    end
    
    if string.len(text:gsub("<span[^>/]*>.-</span>", ""):gsub("%b<>","")) <= 2 then
        z.error_categories = {};
        text = seterror('empty_citation');
        z.message_tail = {};
    end
    
    if is_set(options.id) then 
        text = '<span id="' .. mw.uri.anchorEncode(options.id) ..'" class="' .. mw.text.nowiki(options.class) .. '">' .. text .. "</span>";
    else
        text = '<span class="' .. mw.text.nowiki(options.class) .. '">' .. text .. "</span>";
    end        

    local empty_span = '<span style="display:none;">&nbsp;</span>';
    
    -- Note: Using display: none on then 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 .. errorcomment( v[1], v[2] );
                else
                    text = text .. errorcomment( v[1] .. "; ", v[2] );
                end
            end
        end
    end
    
    no_tracking_cats = no_tracking_cats:lower();
    if inArray(no_tracking_cats, {"", "no", "false", "n"}) then
        for _, v in ipairs( z.error_categories ) do
            text = text .. '[[Category:' .. v ..']]';
        end
    end
    
    return text
end

-- This is used by templates such as {{cite book}} to create the actual citation text.
function z.citation(frame)
    local pframe = frame:getParent()
    
    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    

    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 = seterror( 'text_ignored', {v}, true );
                    end
                elseif validate( k:lower() ) then 
                    error_text, error_state = seterror( 'parameter_ignored_suggest', {k, k:lower()}, true );
                else
                    if #suggestions == 0 then
                        suggestions = mw.loadData( 'Module:Citation/CS1/Suggestions' );
                    end
                    if suggestions[ k:lower() ] ~= nil then
                        error_text, error_state = seterror( 'parameter_ignored_suggest', {k, suggestions[ k:lower() ]}, true );
                    else
                        error_text, error_state = seterror( 'parameter_ignored', {k}, true );
                    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    
    
    return citation0( config, args)
end

return z