عرض مصدر وحدة:استشهاد برأي/أسلوب استشهاد برأي 1

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

-- Include translation message hooks, ID and error handling configuration settings.
local cfg = mw.loadData( '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

--[[
Categorize and emit an error message when the citation contains one or more deprecated parameters.  Because deprecated parameters (currently |day=, |month=,
|coauthor=, and |coauthors=) aren't related to each other and because these parameters may be concatenated into the variables used by |date= and |author#= (and aliases)
details of which parameter caused the error message are not provided.  Only one error message is emitted regarless of the number of deprecated parameters in the citation.
]]
function deprecated_parameter()
	if true ~= Page_in_deprecated_cat then	-- if we haven't been here before then set a 
		Page_in_deprecated_cat=true;		-- sticky flag so that if there are more than one deprecated parameter the category is added only once
		table.insert( z.message_tail, { seterror( 'deprecated_params', {error_message}, true ) } );		-- add error message
	end
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;
	return args and mw.message.newRawMessage( msg, args ):plain() or msg;
end

--[[
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)
]]
function kern_quotes (str)
	local left='<span style="padding-left:0.2em;">%1</span>';		-- spacing to use when title contains leading single or double quote mark
	local right='<span style="padding-right:0.2em;">%1</span>';		-- spacing to use when title contains trailing single or double quote mark
	
	if  str:match ("^[\"\'][^\']") then
		str = string.gsub( str, "^[\"\']", left, 1 );				-- replace (captured) leading single or double quote with left-side <span>
	end
	if str:match ("[^\'][\"\']$") then
		str = string.gsub( str, "[\"\']$", right, 1 );			-- replace (captured) trailing single or double quote with right-side <span>
	end
	return str;
end

-- Wraps a string using a message_list configuration taking one argument
function wrap( key, str, lower )
    if not is_set( str ) then
        return "";
    elseif inArray( key, { 'italic-title', 'trans-italic-title' } ) then
        str = safeforitalics( str );
    end
    if lower == true then
        return substitute( cfg.messages[key]:lower(), {str} );
    else
        return substitute( cfg.messages[key], {str} );
    end        
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 type( list ) == 'table' then
                v, origin[k] = selectone( 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

--[[
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
]]
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 ();				-- 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 ();				-- 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 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 "&nbsp;",
        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 "&nbsp;",
        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

--[[
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.
]]
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 = ' ' .. seterror( '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 = ' ' .. seterror( 'bad_pmid' );	-- set an error message
		end
	end
	
	return externallinkid({link = handler.link, label = handler.label,
			prefix=handler.prefix,id=id,separator=handler.separator, encode=handler.encode}) .. err_cat;
end

--[[
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 true; otherwse, returns false because the embargo has expired or |embargo= not set in this cite.
]]
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 and tonumber( embargo_date ) >= tonumber( todays_date ) then	--is embargo date is in the future?
			return true;	-- still embargoed
		end
	end
	return false;			-- embargo expired or |embargo= not set
end

--[[
Formats a PMC and checks 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 specifies a date 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.
]]
function pmc(id, embargo)
	local handler = cfg.id_handlers['PMC'];
    
	local text;

	if is_embargoed(embargo) then
		text="[[" .. handler.link .. "|" .. handler.label .. "]]:" .. handler.separator .. id;	--still embargoed so no external link
	else
		text = externallinkid({link = handler.link, label = handler.label,			--no embargo date, ok to link to article
			prefix=handler.prefix,id=id,separator=handler.separator, encode=handler.encode})
	end
	return text;
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
		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 = externallinkid({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–]-[^%.,]$") then	-- doi must begin with '10.', must not contain spaces or endashes, and must not end with period or comma
		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

--[[
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.
]]
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 ndashes from the issn

	if 8 ~= id:len() or nil == id:match( "^%d*X?$" ) then		-- validate the issn: 8 didgits 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 = externallinkid({link = handler.link, label = handler.label,
		prefix=handler.prefix,id=id,separator=handler.separator, encode=handler.encode})
 
	if false == valid_issn then
		text = text .. ' ' .. seterror( 'bad_issn' )			-- add an error message if the issn is invalid
	end 
	
	return text
end

--[[
This function sets default title types (equivalent to the citation including |type=<default value>) for those citations that have defaults.
Also handles the special case where it is desireable to omit the title type from the rendered citation (|type=none).
]]
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

	if "podcast" == cite_class then				-- if this citation is cite podcast
		return "Podcast";						-- display podcast annotation

	elseif "pressrelease" == cite_class then	-- if this citation is cite press release
		return "Press release";					-- display press release annotation

	elseif "techreport" == cite_class then		-- if this citation is cite techreport
		return "Technical report";				-- display techreport annotation
	
	elseif "thesis" == cite_class then			-- if this citation is cite thesis (degree option handled after this function returns)
			return "Thesis";					-- display simple thesis annotation (without |degree= modification)
	end
end

-- returns a number according to the month in a date: 1 for January, etc.  Capitalization and spelling must be correct. If not a valid month, returns 0
function get_month_number (month)
local long_months = {['January']=1, ['February']=2, ['March']=3, ['April']=4, ['May']=5, ['June']=6, ['July']=7, ['August']=8, ['September']=9, ['October']=10, ['November']=11, ['December']=12};
local short_months = {['Jan']=1, ['Feb']=2, ['Mar']=3, ['Apr']=4, ['May']=5, ['Jun']=6, ['Jul']=7, ['Aug']=8, ['Sep']=9, ['Oct']=10, ['Nov']=11, ['Dec']=12};
local temp;
	temp=long_months[month];
	if temp then return temp; end				-- if month is the long-form name
	temp=short_months[month];
	if temp then return temp; end				-- if month is the short-form name
	return 0;									-- misspelled, improper case, or not a month name
end

-- returns a number according to the sequence of seasons in a year: 1 for Winter, etc.  Capitalization and spelling must be correct. If not a valid season, returns 0
function get_season_number (season)
local season_list = {['Winter']=1, ['Spring']=2, ['Summer']=3, ['Fall']=4, ['Autumn']=4}
local temp;
	temp=season_list[season];
	if temp then return temp; end				-- if season is a valid name return its number
	return 0;									-- misspelled, improper case, or not a season name
end

--[[
Returns true if day is less than or equal to the number of days in month; else returns false.

Assumes Julian calendar prior to year 1582 and Gregorian calendar thereafter. Accounts for Julian calendar leap years before 1582 and Gregorian leap years after 1582.
Where the two calendars overlap (1582 to approximately 1923) dates are assumed to be Gregorian.
]]
function is_valid_date (year, month, day)
local days_in_month = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
local month_length;
	if (2==month) then							-- if February
		month_length = 28;						-- then 28 days unless
		if 1582 > tonumber(year) then			-- Julian calendar
			if 0==(year%4) then
				month_length = 29;
			end
		else									-- Gregorian calendar
			if (0==(year%4) and (0~=(year%100) or 0==(year%400))) then	-- is a leap year?
				month_length = 29;				-- if leap year then 29 days in February
			end
		end
	else
		month_length=days_in_month[month];
	end

	if tonumber (day) > month_length then
		return false;
	end
	return true;
end

--[[
Check a pair of months or seasons to see if both are valid members of a month or season pair.

Month pairs are expected to be left to right, earliest to latest in time.  Similarly, seasons are also left to right, earliest to latest in time.  There is
an oddity with seasons.  Winter is assigned a value of 1, spring 2, ..., fall and autumn 4.  Because winter can follow fall/autumn at the end of a calender year, a special test
is made to see if |date=Fall-Winter yyyy (4-1) is the date.
]]

function is_valid_month_season_range(range_start, range_end)
	local range_start_number = get_month_number (range_start);
	
	if 0 == range_start_number then								-- is this a month range?
		local range_start_number = get_season_number (range_start);		-- not a month; is it a season? get start season number
		local range_end_number = get_season_number (range_end);			-- get end season number

		if 0 ~= range_start_number then							-- is start of range a season?
			if range_start_number < range_end_number then		-- range_start is a season
				return true;									-- return true when range_end is also a season and follows start season; else false
			end
			if 4 == range_start_number and 1 == range_end_number then	-- special case when range is Fall-Winter or Autumn-Winter
				return true;
			end
		end
		return false;		-- range_start is not a month or a season; or range_start is a season and range_end is not; or improper season sequence
	end

	local range_end_number = get_month_number (range_end);		-- get end month number
	if range_start_number < range_end_number then				-- range_start is a month; does range_start precede range_end?
		return true;											-- if yes, return true
	end
	return false;												-- range_start month number is greater than or equal to range end number; or range end isn't a month
end

--[[
Check date format to see that it is one of the formats approved by MOS:DATE: MMMM D, YYYY; D MMMM YYYY; MMMM YYYY; YYYY-MM-DD; YYYY.
Additionally, check the date to see that it is a real date: no 31 in 30-day months; no 29 February when not a leap year.  Months, both long-form and three
character abbreviations, and seasons must be spelled correctly.

If the date fails the fomat tests, this function returns false but does not return values for anchor_year and COinS_date.  When this happens, the date parameter is
used in the COinS metadata and the CITEREF identifier gets its year from the year parameter if present.

Inputs:
	date_string - date string from date-holding parameters (date, year, accessdate, embargo, archivedate, etc)

Returns:
	false if date string is not a real date; else
	true, anchor_year, COinS_date
		anchor_year can be used in CITEREF anchors
		COinS_date is date_string without anchor_year disambiguator if any
]]
function check_date (date_string)
	local year;
	local month=0;		-- assume that month and day are not used; if either is zero then final year/month/day validation is not necessary
	local day=0;
	local day2=0;		-- second day in a day range	
	local anchor_year;
	local coins_date;

	if date_string:match("^%d%d%d%d%-%d%d%-%d%d$") then			-- Year-initial numerical year month day format
		year, month, day=string.match(date_string, "(%d%d%d%d)%-(%d%d)%-(%d%d)");
		month=tonumber(month);
		if 12 < month or 1 > month or 1583 > tonumber(year) then return false; end	-- month number not valid or not Gregorian calendar
		anchor_year = year;

	elseif date_string:match("^%a+ +[1-9]%d?, +[1-9]%d%d%d%a?$") then	-- month-initial: month day, year
		month, day, anchor_year, year=string.match(date_string, "(%a+)%s*(%d%d?),%s*((%d%d%d%d)%a?)");
		month = get_month_number (month);
		if 0 == month then return false; end					-- return false if month text isn't one of the twelve months
				
	elseif date_string:match("^%a+ +[1-9]%d?–[1-9]%d?, +[1-9]%d%d%d%a?$") then	-- month-initial day range: month day–day, year; days are separated by endash
		month, day, day2, anchor_year, year=string.match(date_string, "(%a+) +(%d%d?)–(%d%d?), +((%d%d%d%d)%a?)");
		if tonumber(day) >= tonumber(day2) then return false; end				-- date range order is left to right: earlier to later; dates may not be the same;
		month = get_month_number (month);
		if 0 == month then return false; end					-- return false if month text isn't one of the twelve months

	elseif date_string:match("^[1-9]%d? +%a+ +[1-9]%d%d%d%a?$") then		-- day-initial: day month year
		day, month, anchor_year, year=string.match(date_string, "(%d%d*)%s*(%a+)%s*((%d%d%d%d)%a?)");
		month = get_month_number (month);
		if 0 == month then return false; end					-- return false if month text isn't one of the twelve months

	elseif date_string:match("^[1-9]%d?–[1-9]%d? +%a+ +[1-9]%d%d%d%a?$") then	-- day-range-initial: day–day month year; days are separated by endash
		day, day2, month, anchor_year, year=string.match(date_string, "(%d%d?)–(%d%d?) +(%a+) +((%d%d%d%d)%a?)");
		if tonumber(day) >= tonumber(day2) then return false; end				-- date range order is left to right: earlier to later; dates may not be the same;
		month = get_month_number (month);
		if 0 == month then return false; end					-- return false if month text isn't one of the twelve months

	elseif mw.ustring.match (date_string, "^%a+–%a+ +[1-9]%d%d%d%a?$") then		-- month/season range year; months separated by endash 
		local month2
		month, month2, anchor_year, year=mw.ustring.match (date_string, "(%a+)[%-/–](%a+)%s*((%d%d%d%d)%a?)");
		if false == is_valid_month_season_range(month, month2) then
			return false;
		end
		
	elseif date_string:match("^%a+ +%d%d%d%d%a?$") then			-- month/season year
		month, anchor_year, year=string.match(date_string, "(%a+)%s*((%d%d%d%d)%a?)");
		if 0 == get_month_number (month) then					-- if month text isn't one of the twelve months, might be a season
			if 0 == get_season_number (month) then				-- not a month, is it a season?
				return false;									-- return false not a month or one of the five seasons
			end
		end

	elseif date_string:match("^[1-9]%d%d%d?%a?$") then			-- year; here accept either YYY or YYYY
		anchor_year, year=string.match(date_string, "((%d%d%d%d?)%a?)");

	else
		return false;											-- date format not one of the MOS:DATE approved formats
	end

	if 0~=month and 0~=day then									-- check year month day dates for validity
		if 0~=day2 then											-- If there is a second day (d–d Mmm YYYY or Mmm d–d, YYYY) test the second date
			if false==is_valid_date(year,month,day2) then
				return false;									-- second date in date range string is not a real date return false; unset anchor_year and coins_date
			end													-- if second date range string is valid, fall through to test the first date range
		end
		if false==is_valid_date(year,month,day) then
			return false;										-- date string is not a real date return false; unset anchor_year and coins_date
		end
	end

	coins_date= mw.ustring.gsub( date_string, "–", "-" );		-- if here, then date_string is valid; set coins_date and replace any ndash with a hyphen
	
	return true, anchor_year, coins_date;						-- format is good and date string represents a real date
end	

--[[
Cycle the date-holding parameters in passed table date_parameters_list through check_date() to check compliance with MOS:DATE. For all valid dates, check_date() returns
true and values for anchor_year (used in CITEREF identifiers) and COinS_date (used in the COinS metadata).  The |date= parameter test is unique.  This function only 
accepts anchor_year and COinS_date results from the |date= parameter test and |date= is the only date-holding parameter that is allowed to contain the no-date keywords
"n.d." or "nd" (without quotes).

Unlike most error messages created in this module, only one error message is created by this function. Because all of the date holding parameters are processed serially,
a single error message is created as the dates are tested.
]]

function dates(date_parameters_list)
	local anchor_year;		-- will return as nil if the date being tested is not |date=
	local COinS_date;		-- will return as nil if the date being tested is not |date=
	local error_message ="";
	local good_date=false;
	
	for k, v in pairs(date_parameters_list) do		-- for each date-holding parameter in the list
		if is_set(v) then							-- if the parameter has a value
			if v:match("^c%. [1-9]%d%d%d?%a?$") then	-- special case for c. year or with or without CITEREF disambiguator - only |date= and |year=
				if 'date'==k then
					good_date, anchor_year, COinS_date = true, v:match("((c%. [1-9]d%d%d?)%a?)");	-- anchor year and COinS_date only from |date= parameter
				elseif 'year'==k then
					good_date =  true;
				end
			elseif 'year'==k then					-- if the parameter is |year= (but not c. year)
				if v:match("^[1-9]%d%d%d?%a?$") then	-- year with or without CITEREF disambiguator
					good_date =  true;
				end
			elseif 'date'==k then					-- if the parameter is |date=
				if v:match("n%.d%.%a?") then		-- if |date=n.d. with or without a CITEREF disambiguator
					good_date, anchor_year, COinS_date = true, v:match("((n%.d%.)%a?)");	--"n.d."; no error when date parameter is set to no date
				elseif v:match("nd%a?$") then		-- if |date=nd with or without a CITEREF disambiguator
					good_date, anchor_year, COinS_date = true, v:match("((nd)%a?)");	--"nd";	no error when date parameter is set to no date
				else
					good_date, anchor_year, COinS_date = check_date (v);	-- go test the date
				end
			else									-- any other date-holding parameter
				good_date = check_date (v);			-- go test the date
			end
			if false==good_date then				-- assemble one error message so we don't add the tracking category multiple times
				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
	end
	if is_set(error_message) then
		table.insert( z.message_tail, { seterror( 'bad_date', {error_message}, true ) } );	-- add this error message
	end

	return anchor_year, COinS_date;		-- and done
end

--[[
Determines whether a 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

--[[
ISBN-10 and ISSN validator code calculates checksum across all isbn/issn digits including the check digit. ISBN-13 is checked in checkisbn().
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.
]]
function is_valid_isxn (isxn_str, len)
	local temp = 0;
	isxn_str = { isxn_str:byte(1, len) };	-- make a table of bytes
	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
			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

-- Determines whether an ISBN string is valid
function checkisbn( 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
		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]', {    
        ['['] = '&#91;',
        [']'] = '&#93;',
        ['\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  

-- 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 == '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 == 'ISSN' then
        	table.insert( new_list, {handler.label, issn( 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 )	-- 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
  
-- 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 doing 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 Degree = A['Degree'];
    local Docket = A['Docket'];
    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'];

--[[
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

All other combinations of |encyclopedia, |title, and |article are not modified
]]
	if ( config.CitationClass == "encyclopaedia" ) then
		if is_set(Periodical) then					-- Periodical is set when |encyclopedia is set
			if is_set(Title) then
				if not is_set(Chapter) then
					Chapter = Title;				-- |encyclopedia and |title are set so map |title to |article and |encyclopedia to |title
					TransChapter = TransTitle;
					Title = Periodical;
					Periodical = '';				-- redundant so unset
					TransTitle = '';				-- redundant so unset
				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

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 RegistrationRequired = A['RegistrationRequired'];
    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'];
	
-- Special case for cite techreport.
	local ID = A['ID'];
	if (config.CitationClass == "techreport") then	-- special case for cite techreport
		if is_set(Issue) then						-- cite techreport uses 'number', which other citations aliase to 'issue'
			if not is_set(ID) then					-- can we use ID for the "number"?
				ID = Issue;							-- yes, use it
				Issue = "";							-- unset Issue so that "number" isn't duplicated in the rendered citation or COinS metadata
			else									-- can't use ID so emit error message
				ID = ID .. " " .. seterror('redundant_parameters', '<code>&#124;id=</code> and <code>&#124;number=</code>');
			end
		end	
	end	
			
    local ASINTLD = A['ASINTLD'];
    local IgnoreISBN = A['IgnoreISBN'];
    local Embargo = A['Embargo'];

    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 use_lowercase = ( sepc ~= '.' );
    local this_page = mw.title.getCurrentTitle();  --Also used for COinS and for language
    
    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

	local anchor_year;		-- used in the CITEREF identifier
	local COinS_date;		-- used in the COinS metadata

-- legacy: promote concatenation of |day=, |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 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
		elseif is_set(PublicationDate) then	-- use PublicationDate when |date= and |year= are not set
			Date = PublicationDate;			-- promonte 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.
-- TODO: 2013-10-27: AirDate is nil when dates() is called because it hasn't been set yet.  Move the call to dates() or set AirDate earlier.
	anchor_year, COinS_date = dates({['accessdate']=AccessDate, ['airdate']=AirDate, ['archivedate']=ArchiveDate, ['date']=Date, ['doi_brokendate']=DoiBroken,
		['embargo']=Embargo, ['laydate']=LayDate, ['publicationdate']=PublicationDate, ['year']=Year});

-- 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 journal}} with |pmc= set and |url= not set
	if config.CitationClass == "journal" and not is_set(URL) and is_set(ID_list['PMC']) then
		if not is_embargoed(Embargo) then
			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

    -- 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(COinS_date, Date),		-- COinS_date has correctly formatted date if Date is valid; any reason to keep Date here?  Should we be including invalid dates in metadata?
        ['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

	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, { seterror('coauthors_missing_author', {}, true) } );	-- emit error message
	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

    local Cartography = "";
    local Scale = "";
    if config.CitationClass == "map" then
        if not is_set( Authors ) and is_set( PublisherName ) then
            Authors = PublisherName;
            PublisherName = "";
        end
        Cartography = A['Cartography'];
        if is_set( Cartography ) then
            Cartography = sepc .. " " .. wrap( 'cartography', Cartography, use_lowercase );
        end        
        Scale = A['Scale'];
        if is_set( Scale ) then
            Scale = sepc .. " " .. Scale;
        end        
    end
    
    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 or cite podcast |url= is missing or empty 
		if inArray(config.CitationClass, {"web","podcast"}) 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 = kern_quotes (Chapter);				-- if necessary, separate chapter title's leading and trailing quote marks from Module provided quote marks
        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 = kern_quotes (Title);				-- if necessary, separate title's leading and trailing quote marks from Module provided quote marks
        Title = wrap( 'quoted-title', Title );
        TransTitle = wrap( 'trans-quoted-title', TransTitle );
    elseif inArray(config.CitationClass, {"web","news","pressrelease","conference","podcast"}) and
            not is_set(Chapter) then
		Title = kern_quotes (Title);				-- if necessary, separate title's leading and trailing quote marks from Module provided quote marks
        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
        Place = " " .. wrap( 'written', Place, use_lowercase ) .. sepc .. " ";
    end
    
    if is_set(Conference) then
        if is_set(ConferenceURL) then
            Conference = externallink( ConferenceURL, Conference );
        end
        Conference = sepc .. " " .. Conference
    elseif is_set(ConferenceURL) then
        Conference = sepc .. " " .. 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","podcast"}) 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","podcast"}) then
            Page = ": " .. Page;
        else
            Page = sepc .." " .. PPrefix .. Page;
        end
    end
    
    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 Inset = A['Inset'];
        if first_set( Pages, Page, At ) ~= nil or sepc ~= '.' then
            if is_set( Section ) then
                Section = ", " .. wrap( 'section', Section, true );
            end
            if is_set( Inset ) then
                Inset = ", " .. wrap( 'inset', Inset, true );
            end
        else
            if is_set( Section ) then
                Section = sepc .. " " .. wrap( 'section', Section, use_lowercase );
                if is_set( Inset ) then
                    Inset = ", " .. wrap( 'inset', Inset, true );
                end
            elseif is_set( Inset ) then
                Inset = sepc .. " " .. wrap( 'inset', Inset, use_lowercase );
            end            
        end            
        At = At .. Section .. Inset;        
    end    

	--[[Look in the list of iso639-1 language codes to see if the value provided in the language parameter matches one of them.  If a match is found, 
	use that value; if not, then use the value that was provided with the language parameter.
	
	Categories are assigned in a manner similar to the {{xx icon}} templates - categorizes only mainspace citations and only when the language code is not 'en' (English).
	]]
	if is_set (Language) then
--		local name = mw.language.fetchLanguageName( Language:lower(), "en" );	-- experiment: this seems to return correct ISO 639-1 language names
		local name = cfg.iso639_1[Language:lower()];		-- get the language name if Language parameter has a valid iso 639-1 code
		if nil == name then
			Language=" " .. wrap( 'language', Language );	-- no match, use parameter's value
		else
			if 0 == this_page.namespace and 'en' ~= Language:lower() then	--found a match; is this page main / article space and English not the language?
				Language=" " .. wrap( 'language', name .. '[[Category:Articles with ' .. name .. '-language external links]]' );	-- in main space and not English: categorize
			else
				Language=" " .. wrap( 'language', name );	--not in mainspace or language is English so don't categorize
			end
		end
	else
		Language="";	-- language not specified so make sure this is an empty string;
	end

	Others = is_set(Others) and (sepc .. " " .. Others) or "";

-- handle type parameter for those CS1 citations that have default values

	if inArray(config.CitationClass, {"podcast","pressrelease","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 = " (" .. TitleType .. ")";	-- display it in parentheses
	end

	TitleNote = is_set(TitleNote) and (sepc .. " " .. TitleNote) 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
    --[[ Loosely mimic {{subscription required}} template; Via parameter identifies a delivery source that is not the publisher; these sources often, but not always, exist
    behind a registration or paywall.  So here, we've chosen to decouple via from subscription (via has never been part of the registration required template).
    
    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(Via) then
        Via = " " .. wrap( 'via', Via );
    end

	if is_set(SubscriptionRequired) then
        SubscriptionRequired = sepc .. " " .. cfg.messages['subscription']; --here when 'via' parameter not used but 'subscription' is
    elseif is_set(RegistrationRequired) then
        SubscriptionRequired = sepc .. " " .. cfg.messages['registration']; --here when 'via' and 'subscription' parameters not used but 'registration' is
    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(ID) then ID = sepc .." ".. ID; end
   	if "thesis" == config.CitationClass and is_set(Docket) then
		ID = sepc .." Docket ".. Docket .. ID;
	end

    
    ID_list = buildidlist( ID_list, {DoiBroken = DoiBroken, ASINTLD = ASINTLD, IgnoreISBN = IgnoreISBN, Embargo=Embargo} );

    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","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( '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

--[[
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
    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, Scale, Series, 
            Language, Cartography, Edition, Publisher, Agency, Volume, Issue}, sepc );
    else 
        tcommon = safejoin( {Title, TitleNote, Conference, Periodical, Format, TitleType, Scale, Series, Language, 
            Volume, Issue, Others, Cartography, Edition, Publisher, Agency}, 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 = Position .. 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 = " ";
            local post_text = "";
            if is_set(Chapter) then
                in_text = in_text .. cfg.messages['in'] .. " "
            else
                if EditorCount <= 1 then
                    post_text = ", " .. cfg.messages['editor'];
                else
                    post_text = ", " .. cfg.messages['editors'];
                end
            end 
            if (sepc ~= '.') then in_text = in_text:lower() end
            Editors = in_text .. Editors .. post_text;
            if (string.sub(Editors,-1,-1) == sepc)
                then Editors = Editors .. " "
                else Editors = 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
    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 #a > 0 then
                for i,v in ipairs(a) do 
                    names[i] = v.last 
                    if i == 4 then break end
                end
            elseif #e > 0 then
                for i,v in ipairs(e) do 
                    names[i] = v.last 
                    if i == 4 then break end                
                end
            end
			names[ #names + 1 ] = first_set(Year, anchor_year);	-- Year first for legacy citations
            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