--[[--------------------------< F O R W A R D   D E C L A R A T I O N S >-------------------------------------- ]]  local bn = require('মডিউল:সংখ্যা রূপান্তরকারী')._translate2bn local en = require('মডিউল:সংখ্যা রূপান্তরকারী')._translate2en  local has_accept_as_written, is_set, in_array, set_message, select_one,			-- functions in Module:Citation/CS1/Utilities 		substitute, make_wikilink;  local z;																		-- table of tables defined in Module:Citation/CS1/Utilities  local cfg;																		-- table of configuration tables that are defined in Module:Citation/CS1/Configuration  --[[--------------------------< P A G E   S C O P E   V A R I A B L E S >--------------------------------------  declare variables here that have page-wide scope that are not brought in from other modules; that are created here and used here  ]]  local auto_link_urls = {};														-- holds identifier URLs for those identifiers that can auto-link |title=  --============================<< H E L P E R   F U N C T I O N S >>============================================  --[[--------------------------< W I K I D A T A _ A R T I C L E _ N A M E _ G E T >----------------------------  as an aid to internationalizing identifier-label wikilinks, gets identifier article names from Wikidata.  returns :<lang code>:<article title> when <q> has an <article title> for <lang code>; nil else  for identifiers that do not have q, returns nil  for wikis that do not have mw.wikibase installed, returns nil  ]]  local function wikidata_article_name_get (q) 	if not is_set (q) or (q and not mw.wikibase) then							-- when no q number or when a q number but mw.wikibase not installed on this wiki 		return nil;																-- abandon 	end  	local wd_article; 	local this_wiki_code = cfg.this_wiki_code;									-- Wikipedia subdomain; 'en' for en.wikipedia.org  	wd_article = mw.wikibase.getSitelink (q, this_wiki_code .. 'wiki');			-- fetch article title from WD; nil when no title available at this wiki  	if wd_article then 		wd_article = table.concat ({':', this_wiki_code, ':', wd_article});		-- interwiki-style link without brackets if taken from WD; leading colon required 	end  	return wd_article;															-- article title from WD; nil else end  --[[--------------------------< L I N K _ L A B E L _ M A K E >------------------------------------------------  common function to create identifier link label from handler table or from Wikidata  returns the first available of 	1. redirect from local wiki's handler table (if enabled) 	2. Wikidata (if there is a Wikidata entry for this identifier in the local wiki's language) 	3. label specified in the local wiki's handler table 	 ]]  local function link_label_make (handler) 	local wd_article; 	 	if not (cfg.use_identifier_redirects and is_set (handler.redirect)) then	-- redirect has priority so if enabled and available don't fetch from Wikidata because expensive 		wd_article = wikidata_article_name_get (handler.q);						-- if Wikidata has an article title for this wiki, get it; 	end 	 	return (cfg.use_identifier_redirects and is_set (handler.redirect) and handler.redirect) or wd_article or handler.link; end  --[[--------------------------< E X T E R N A L _ L I N K _ I D >----------------------------------------------  Formats a wiki-style external link  ]]  local function external_link_id (options) 	local url_string = options.id; 	local ext_link; 	local this_wiki_code = cfg.this_wiki_code;									-- Wikipedia subdomain; 'en' for en.wikipedia.org 	local wd_article;															-- article title from Wikidata 	 	if options.encode == true or options.encode == nil then 		url_string = mw.uri.encode (url_string, 'PATH'); 	end  	if options.auto_link and is_set (options.access) then 		auto_link_urls[options.auto_link] = table.concat ({options.prefix, url_string, options.suffix}); 	end  	ext_link = mw.ustring.format ('[%s%s%s %s]', options.prefix, url_string, options.suffix or "", mw.text.nowiki (options.id)); 	if is_set (options.access) then 		ext_link = substitute (cfg.presentation['ext-link-access-signal'], {cfg.presentation[options.access].class, cfg.presentation[options.access].title, ext_link});	-- add the free-to-read / paywall lock 	end  	return table.concat	({ 		make_wikilink (link_label_make (options), options.label),				-- redirect, Wikidata link, or locally specified link (in that order) 		options.separator or ' ', 		ext_link 		}); end  --[[--------------------------< I N T E R N A L _ L I N K _ I D >----------------------------------------------  Formats a wiki-style internal link  TODO: Does not currently need to support options.access, options.encode, auto-linking and COinS (as in external_link_id), but may be needed in the future for :m:Interwiki_map custom-prefixes like :arxiv:, :bibcode:, :DOI:, :hdl:, :ISSN:, JSTOR:, :Openlibrary:, :PMID:, :RFC:.  ]]  local function internal_link_id (options) 	local id = mw.ustring.gsub (options.id, '%d', cfg.date_names.local_digits);	-- translate 'local' digits to Western 0-9  	return table.concat ( 		{ 		make_wikilink (link_label_make (options), options.label),				-- wiki-link the identifier label 		options.separator or ' ',											-- add the separator 		make_wikilink ( 			table.concat ( 				{ 				options.prefix, 				en(id),																-- translated to Western digits 				options.suffix or 				}), 			bn(substitute (cfg.presentation['bdi'], {, mw.text.nowiki (options.id)}))	-- bdi tags to prevent Latin script identifiers from being reversed at RTL language wikis 			);																	-- nowiki because MediaWiki still has magic links for ISBN and the like; TODO: is it really required? 		}); end  --[[--------------------------< I S _ E M B A R G O E D >------------------------------------------------------  Determines if a PMC identifier's online version is embargoed. Compares the date in |pmc-embargo-date= against today's date.  If embargo date is in the future, returns the content of |pmc-embargo-date=; otherwise, returns an empty string because the embargo has expired or because |pmc-embargo-date= was not set in this cite.  ]]  local function is_embargoed (embargo) 	if is_set (embargo) then 		local lang = mw.getContentLanguage(); 		local good1, embargo_date, todays_date; 		good1, embargo_date = pcall (lang.formatDate, lang, 'U', embargo); 		todays_date = lang:formatDate ('U'); 	 		if good1 then															-- if embargo date is a good date 			if tonumber (embargo_date) >= tonumber (todays_date) then			-- is embargo date is in the future? 				return embargo;													-- still embargoed 			else 				set_message ('maint_pmc_embargo');								-- embargo has expired; add main cat 				return ;														-- unset because embargo has expired 			end 		end 	end 	return ;																	-- |pmc-embargo-date= not set return empty string end  --[=[-------------------------< I S _ V A L I D _ R X I V _ D A T E >------------------------------------------  for biorxiv, returns true if: 	2019-12-11T00:00Z <= biorxiv_date < today + 2 days for medrxiv, returns true if: 	2020-01-01T00:00Z <= medrxiv_date < today + 2 days 	 The dated form of biorxiv identifier has a start date of 2019-12-11.  The Unix timestamp for that date is  = 1576022400 The medrxiv identifier has a start date of 2020-01-01.  The Unix timestamp for that date is  = 1577836800  <rxiv_date> is the date provided in those |biorxiv= parameter values that are dated and in |medrxiv= parameter values at time 00:00:00 UTC <today> is the current date at time 00:00:00 UTC plus 48 hours 	if today's date is 2023-01-01T00:00:00 then 		adding 24 hours gives 2023-01-02T00:00:00 – one second more than today 		adding 24 hours gives 2023-01-03T00:00:00 – one second more than tomorrow  inputs: 	<y>, <m>, <d> – year, month, day parts of the date from the birxiv or medrxiv identifier 	<select> 'b' for biorxiv, 'm' for medrxiv; defaults to 'b'  ]=]  local function is_valid_rxiv_date (y, m, d, select) 	if 0 == tonumber (m) and 12 < tonumber (m) then								-- <m> must be a number 1–12 		return false; 	end 	if 0 == tonumber (d) and 31 < tonumber (d) then								-- <d> must be a number 1–31; TODO: account for month length and leap yer? 		return false; 	end 	 	local rxiv_date = table.concat ({y, m, d}, '-');							-- make ymd date string 	local good1, good2; 	local rxiv_ts, tomorrow_ts;													-- to hold Unix timestamps representing the dates 	local lang_object = mw.getContentLanguage();  	good1, rxiv_ts = pcall (lang_object.formatDate, lang_object, 'U', rxiv_date);		-- convert rxiv_date value to Unix timestamp  	good2, tomorrow_ts = pcall (lang_object.formatDate, lang_object, 'U', 'today + 2 days' );	-- today midnight + 2 days is one second more than all day tomorrow 	 	if good1 and good2 then														-- lang.formatDate() returns a timestamp in the local script which tonumber() may not understand 		rxiv_ts = tonumber (rxiv_ts) or lang_object:parseFormattedNumber (rxiv_ts);	-- convert to numbers for the comparison; 		tomorrow_ts = tonumber (tomorrow_ts) or lang_object:parseFormattedNumber (tomorrow_ts); 	else 		return false;															-- one or both failed to convert to Unix timestamp 	end  	local limit_ts = ((select and ('m' == select)) and 1577836800) or 1576022400;	-- choose the appropriate limit timesatmp  	return ((limit_ts <= rxiv_ts) and (rxiv_ts < tomorrow_ts))					-- limit_ts <= rxiv_date < tomorrow's date end  --[[--------------------------< IS _ V A L I D _ I S X N >-----------------------------------------------------  ISBN-10 and ISSN validator code calculates checksum across all ISBN/ISSN digits including the check digit. ISBN-13 is checked in isbn().  If the number is valid the result will be 0. Before calling this function, ISBN/ISSN must be checked for length and stripped of dashes, spaces and other non-ISxN characters.  ]]  local function is_valid_isxn (isxn_str, len) 	local temp = 0; 	isxn_str = { isxn_str:byte(1, len) };										-- make a table of byte values '0' → 0x30 .. '9' → 0x39, 'X' → 0x58 	len = len + 1;																-- adjust to be a loop counter 	for i, v in ipairs (isxn_str) do											-- loop through all of the bytes and calculate the checksum 		if v == string.byte ("X" ) then											-- if checkdigit is X (compares the byte value of 'X' which is 0x58) 			temp = temp + 10 * (len - i);										-- it represents 10 decimal 		else 			temp = temp + tonumber (string.char (v) )*(len-i); 		end 	end 	return temp % 11 == 0;														-- returns true if calculation result is zero end  --[[--------------------------< IS _ V A L I D _ I S X N _ 1 3 >-----------------------------------------------  ISBN-13 and ISMN validator code calculates checksum across all 13 ISBN/ISMN digits including the check digit. If the number is valid, the result will be 0. Before calling this function, ISBN-13/ISMN must be checked for length and stripped of dashes, spaces and other non-ISxN-13 characters.  ]]  local function is_valid_isxn_13 (isxn_str) 	local temp=0; 	 	isxn_str = { isxn_str:byte(1, 13) };										-- make a table of byte values '0' → 0x30 .. '9' → 0x39 	for i, v in ipairs (isxn_str) do 		temp = temp + (3 - 2*(i % 2)) * tonumber (string.char (v) );			-- multiply odd index digits by 1, even index digits by 3 and sum; includes check digit 	end 	return temp % 10 == 0;														-- sum modulo 10 is zero when ISBN-13/ISMN is correct end  --[[--------------------------< N O R M A L I Z E _ L C C N >--------------------------------------------------  LCCN normalization (https://www.loc.gov/marc/lccn-namespace.html#normalization) 1. Remove all blanks. 2. If there is a forward slash (/) in the string, remove it, and remove all characters to the right of the forward slash. 3. If there is a hyphen in the string: 	a. Remove it. 	b. Inspect the substring following (to the right of) the (removed) hyphen. Then (and assuming that steps 1 and 2 have been carried out): 		1. All these characters should be digits, and there should be six or less. (not done in this function) 		2. If the length of the substring is less than 6, left-fill the substring with zeroes until the length is six.  Returns a normalized LCCN for lccn() to validate.  There is no error checking (step 3.b.1) performed in this function.  ]]  local function normalize_lccn (lccn) 	lccn = lccn:gsub ("%s", "");												-- 1. strip whitespace  	if nil ~= string.find (lccn, '/') then 		lccn = lccn:match ("(.-)/");											-- 2. remove forward slash and all character to the right of it 	end  	local prefix 	local suffix 	prefix, suffix = lccn:match ("(.+)%-(.+)");									-- 3.a remove hyphen by splitting the string into prefix and suffix  	if nil ~= suffix then														-- if there was a hyphen 		suffix = string.rep("0", 6-string.len (suffix)) .. suffix;				-- 3.b.2 left fill the suffix with 0s if suffix length less than 6 		lccn = prefix..suffix;													-- reassemble the LCCN 	end 	 	return lccn; end  --============================<< I D E N T I F I E R   F U N C T I O N S >>====================================  --[[--------------------------< A R X I V >--------------------------------------------------------------------  See: https://arxiv.org/help/arxiv_identifier  format and error check arXiv identifier.  There are three valid forms of the identifier: the first form, valid only between date codes 9107 and 0703, is: 	arXiv:<archive>.<class>/<date code><number><version> where: 	<archive> is a string of alpha characters - may be hyphenated; no other punctuation 	<class> is a string of alpha characters - may be hyphenated; no other punctuation; not the same as |class= parameter which is not supported in this form 	<date code> is four digits in the form YYMM where YY is the last two digits of the four-digit year and MM is the month number January = 01 		first digit of YY for this form can only 9 and 0 	<number> is a three-digit number 	<version> is a 1 or more digit number preceded with a lowercase v; no spaces (undocumented) 	 the second form, valid from April 2007 through December 2014 is: 	arXiv:<date code>.<number><version> where: 	<date code> is four digits in the form YYMM where YY is the last two digits of the four-digit year and MM is the month number January = 01 	<number> is a four-digit number 	<version> is a 1 or more digit number preceded with a lowercase v; no spaces  the third form, valid from January 2015 is: 	arXiv:<date code>.<number><version> where: 	<date code> and <version> are as defined for 0704-1412 	<number> is a five-digit number  ]]  local function arxiv (options) 	local id = options.id; 	local class = options.Class;												-- TODO: lowercase? 	local handler = options.handler; 	local year, month, version; 	local err_msg = false;														-- assume no error message 	local text;																	-- output text 	 	if id:match("^%a[%a%.%-]+/[90]%d[01]%d%d%d%d$") or id:match("^%a[%a%.%-]+/[90]%d[01]%d%d%d%dv%d+$") then	-- test for the 9107-0703 format with or without version 		year, month = id:match("^%a[%a%.%-]+/([90]%d)([01]%d)%d%d%d[v%d]*$"); 		year = tonumber (year); 		month = tonumber (month); 		if ((not (90 < year or 8 > year)) or (1 > month or 12 < month)) or		-- if invalid year or invalid month 			((91 == year and 7 > month) or (7 == year and 3 < month)) then		-- if years ok, are starting and ending months ok? 				err_msg = true;													-- flag for error message 		end  	elseif id:match("^%d%d[01]%d%.%d%d%d%d$") or id:match("^%d%d[01]%d%.%d%d%d%dv%d+$") then	-- test for the 0704-1412 with or without version 		year, month = id:match("^(%d%d)([01]%d)%.%d%d%d%d[v%d]*$"); 		year = tonumber (year); 		month = tonumber (month); 		if ((7 > year) or (14 < year) or (1 > month or 12 < month)) or			-- is year invalid or is month invalid? (doesn't test for future years) 			((7 == year) and (4 > month)) then									-- when year is 07, is month invalid (before April)? 				err_msg = true;													-- flag for error message 		end  	elseif id:match("^%d%d[01]%d%.%d%d%d%d%d$") or id:match("^%d%d[01]%d%.%d%d%d%d%dv%d+$") then	-- test for the 1501- format with or without version 		year, month = id:match("^(%d%d)([01]%d)%.%d%d%d%d%d[v%d]*$"); 		year = tonumber (year); 		month = tonumber (month); 		if ((15 > year) or (1 > month or 12 < month)) then						-- is year invalid or is month invalid? (doesn't test for future years) 			err_msg = true;														-- flag for error message 		end  	else 		err_msg = true;															-- not a recognized format; flag for error message 	end  	if err_msg then 		options.coins_list_t['ARXIV'] = nil;									-- when error, unset so not included in COinS 	end 	 	local err_msg_t = {}; 	if err_msg then 		set_message ('err_bad_arxiv'); 	end  	text = external_link_id ({link = handler.link, label = handler.label, q = handler.q, redirect = handler.redirect, 			prefix = handler.prefix, id = id, separator = handler.separator, encode = handler.encode, access = handler.access});  	if is_set (class) then 		if id:match ('^%d+') then 			text = table.concat ({text, ' [class, ' ', class, ']'});	-- external link within square brackets, not wikilink 		else 			set_message ('err_class_ignored'); 		end 	end  	return text; end  --[[--------------------------< B I B C O D E >--------------------------------------------------------------------  Validates (sort of) and formats a bibcode ID.  Format for bibcodes is specified here: https://adsabs.harvard.edu/abs_doc/help_pages/data.html#bibcodes  But, this: 2015arXiv151206696F is apparently valid so apparently, the only things that really matter are length, 19 characters and first four digits must be a year.  This function makes these tests: 	length must be 19 characters 	characters in position 		1–4 must be digits and must represent a year in the range of 1000 – next year 		5 must be a letter 		6–8 must be letter, digit, ampersand, or dot (ampersand cannot directly precede a dot; &. ) 		9–18 must be letter, digit, or dot 		19 must be a letter or dot  ]]  local function bibcode (options) 	local id = options.id; 	local access = options.access; 	local handler = options.handler; 	local ignore_invalid = options.accept; 	local err_type; 	local err_msg = ; 	local year;  	local text = external_link_id ({link = handler.link, label = handler.label, q = handler.q, redirect = handler.redirect, 		prefix = handler.prefix, id = id, separator = handler.separator, encode = handler.encode, 		access = access}); 	 	if 19 ~= id:len() then 		err_type = cfg.err_msg_supl.length; 	else 		year = id:match ("^(%d%d%d%d)[%a][%w&%.][%w&%.][%w&%.][%w.]+[%a%.]$"); 		if not year then														-- if nil then no pattern match 			err_type = cfg.err_msg_supl.value;									-- so value error 		else 			local next_year = tonumber (os.date ('%Y')) + 1;					-- get the current year as a number and add one for next year 			year = tonumber (year);												-- convert year portion of bibcode to a number 			if (1000 > year) or (year > next_year) then 				err_type = cfg.err_msg_supl.year;								-- year out of bounds 			end 			if id:find('&%.') then 				err_type = cfg.err_msg_supl.journal;							-- journal abbreviation must not have '&.' (if it does it's missing a letter) 			end 			if id:match ('.........%.tmp%.') then								-- temporary bibcodes when positions 10–14 are '.tmp.' 				set_message ('maint_bibcode'); 			end 		end 	end  	if is_set (err_type) and not ignore_invalid then							-- if there was an error detected and accept-as-written markup not used 		set_message ('err_bad_bibcode', {err_type}); 		options.coins_list_t['BIBCODE'] = nil;									-- when error, unset so not included in COinS 	end  	return text; end  --[[--------------------------< B I O R X I V >-----------------------------------------------------------------  Format bioRxiv ID and do simple error checking.  Before 2019-12-11, biorXiv IDs were 10.1101/ followed by exactly 6 digits.  After 2019-12-11, biorXiv IDs retained the six-digit identifier but prefixed that with a yyyy.mm.dd. date and suffixed with an optional version identifier.  The bioRxiv ID is the string of characters: 	https://doi.org/10.1101/078733 -> 10.1101/078733 or a date followed by a six-digit number followed by an optional version indicator 'v' and one or more digits: 	https://www.biorxiv.org/content/10.1101/2019.12.11.123456v2 -> 10.1101/2019.12.11.123456v2 	 see https://www.biorxiv.org/about-biorxiv  ]]  local function biorxiv (options) 	local id = options.id; 	local handler = options.handler; 	local err_msg = true;														-- flag; assume that there will be an error 	 	local patterns = { 		'^10%.1101/%d%d%d%d%d%d$',												-- simple 6-digit identifier (before 2019-12-11) 		'^10%.1101/(20%d%d)%.(%d%d)%.(%d%d)%.%d%d%d%d%d%dv%d+$',				-- y.m.d. date + 6-digit identifier + version (after 2019-12-11) 		'^10%.1101/(20%d%d)%.(%d%d)%.(%d%d)%.%d%d%d%d%d%d$',					-- y.m.d. date + 6-digit identifier (after 2019-12-11) 		} 	 	for _, pattern in ipairs (patterns) do										-- spin through the patterns looking for a match 		if id:match (pattern) then 			local y, m, d = id:match (pattern);									-- found a match, attempt to get year, month and date from the identifier  			if m then															-- m is nil when id is the six-digit form 				if not is_valid_rxiv_date (y, m, d, 'b') then					-- validate the encoded date; 'b' for biorxiv limit 					break;														-- date fail; break out early so we don't unset the error message 				end 			end 			err_msg = nil;														-- we found a match so unset the error message 			break;																-- and done 		end 	end																			-- err_cat remains set here when no match  	if err_msg then 		options.coins_list_t['BIORXIV'] = nil;									-- when error, unset so not included in COinS 		set_message ('err_bad_biorxiv');										-- and set the error message 	end 	 	return external_link_id ({link = handler.link, label = handler.label, q = handler.q, redirect = handler.redirect, 			prefix = handler.prefix, id = id, separator = handler.separator, 			encode = handler.encode, access = handler.access}); end  --[[--------------------------< C I T E S E E R X >------------------------------------------------------------  CiteSeerX use their own notion of "doi" (not to be confused with the identifiers resolved via doi.org).  The description of the structure of this identifier can be found at Help_talk:Citation_Style_1/Archive_26#CiteSeerX_id_structure  ]]  local function citeseerx (options) 	local id = options.id; 	local handler = options.handler; 	local matched;  	local text = external_link_id ({link = handler.link, label = handler.label, q = handler.q, redirect = handler.redirect, 		prefix = handler.prefix, id = id, separator = handler.separator, encode = handler.encode, 		access = handler.access}); 	 	matched = id:match ("^10%.1%.1%.[1-9]%d?%d?%d?%.[1-9]%d?%d?%d?$"); 	if not matched then 		set_message ('err_bad_citeseerx' ); 		options.coins_list_t['CITESEERX'] = nil;								-- when error, unset so not included in COinS 	end  	return text; end  --[[--------------------------< D O I >------------------------------------------------------------------------  Formats a DOI and checks for DOI errors.  DOI names contain two parts: prefix and suffix separated by a forward slash. 	Prefix: directory indicator '10.' followed by a registrant code 	Suffix: character string of any length chosen by the registrant  This function checks a DOI name for: prefix/suffix.  If the DOI name contains spaces or endashes, or, if it ends with a period or a comma, this function will emit a bad_doi error message.  DOI names are case-insensitive and can incorporate any printable Unicode characters so the test for spaces, endash, and terminal punctuation may not be technically correct but it appears, that in practice these characters are rarely if ever used in DOI names.  https://www.doi.org/doi_handbook/2_Numbering.html				-- 2.2 Syntax of a DOI name https://www.doi.org/doi_handbook/2_Numbering.html#2.2.2			-- 2.2.2 DOI prefix  ]]  local function doi (options) 	local id = options.id; 	local inactive = options.DoiBroken 	local access = options.access; 	local ignore_invalid = options.accept; 	local handler = options.handler; 	local err_flag;  	local function is_extended_free (registrant, suffix)						-- local function to check those few registrants that are mixed; identifiable by the doi suffix <incipit> 		if cfg.extended_registrants_t[registrant] then							-- if this registrant has known free-to-read extentions 			for _, incipit in ipairs (cfg.extended_registrants_t[registrant]) do	-- loop through the registrant's incipits 				if mw.ustring.find (suffix, '^' .. incipit) then				-- if found 					return true; 				end 			end 		end 	end  	local text; 	if is_set (inactive) then 		local inactive_year = inactive:match("%d%d%d%d");						-- try to get the year portion from the inactive date 		local inactive_month, good;  		if is_set (inactive_year) then 			if 4 < inactive:len() then											-- inactive date has more than just a year (could be anything) 				local lang_obj = mw.getContentLanguage();						-- get a language object for this wiki 				good, inactive_month = pcall (lang_obj.formatDate, lang_obj, 'F', inactive);	-- try to get the month name from the inactive date 				if not good then 					inactive_month = nil;										-- something went wrong so make sure this is unset 				end 			end 		end																		-- otherwise, |doi-broken-date= has something but it isn't a date 		 		if is_set (inactive_year) and is_set (inactive_month) then 			set_message ('maint_doi_inactive_dated', {inactive_year, inactive_month, ' '}); 		elseif is_set (inactive_year) then 			set_message ('maint_doi_inactive_dated', {inactive_year, , }); 		else 			set_message ('maint_doi_inactive'); 		end 		inactive = " (" .. cfg.messages['inactive'] .. ' ' .. inactive .. ')'; 	end  	local suffix; 	local registrant, suffix = mw.ustring.match (id, '^10%.([^/]+)/([^%s–]-[^%.,])$');	-- registrant and suffix set when DOI has the proper basic form  	local registrant_err_patterns = {											-- these patterns are for code ranges that are not supported  		'^[^1-3]%d%d%d%d%.%d+$',												-- 5 digits with subcode (0xxxx, 40000+); accepts: 10000–39999 		'^[^1-7]%d%d%d%d$',														-- 5 digits without subcode (0xxxx, 60000+); accepts: 10000–69999 		'^[^1-9]%d%d%d%.%d+$',												-- 4 digits with subcode (0xxx); accepts: 1000–9999 		'^[^1-9]%d%d%d$',														-- 4 digits without subcode (0xxx); accepts: 1000–9999 		'^%d%d%d%d%d%d+',														-- 6 or more digits 		'^%d%d?%d?$',															-- less than 4 digits without subcode (3 digits with subcode is legitimate) 		'^%d%d?%.[%d%.]+',														-- 1 or 2 digits with subcode 		'^5555$',																-- test registrant will never resolve 		'[^%d%.]',																-- any character that isn't a digit or a dot 		}  	if not ignore_invalid then 		if registrant then														-- when DOI has proper form 			for i, pattern in ipairs (registrant_err_patterns) do				-- spin through error patterns 				if registrant:match (pattern) then								-- to validate registrant codes 					err_flag = set_message ('err_bad_doi');						-- when found, mark this DOI as bad 					break;														-- and done 				end 			end 		else 			err_flag = set_message ('err_bad_doi');								-- invalid directory or malformed 		end 	else 		set_message ('maint_doi_ignore'); 	end  	if err_flag then 		options.coins_list_t['DOI'] = nil;										-- when error, unset so not included in COinS 	else 		if not access and (cfg.known_free_doi_registrants_t[registrant] or is_extended_free (registrant, suffix)) then		-- |doi-access=free not set and <registrant> is known to be free 			set_message ('maint_doi_unflagged_free');							-- set a maint cat 		end 	end 	 	text = external_link_id ({link = handler.link, label = handler.label, q = handler.q, redirect = handler.redirect, 		prefix = handler.prefix, id = id, separator = handler.separator, encode = handler.encode, access = access, 		auto_link = not (err_flag or is_set (inactive) or ignore_invalid) and 'doi' or nil -- do not auto-link when |doi-broken-date= has a value or when there is a DOI error or (to play it safe, after all, auto-linking is not essential) when invalid DOIs are ignored 		}) .. (inactive or );  	return text; end  --[[--------------------------< H D L >------------------------------------------------------------------------  Formats an HDL with minor error checking.  HDL names contain two parts: prefix and suffix separated by a forward slash. 	Prefix: character string using any character in the UCS-2 character set except '/' 	Suffix: character string of any length using any character in the UCS-2 character set chosen by the registrant  This function checks a HDL name for: prefix/suffix.  If the HDL name contains spaces, endashes, or, if it ends with a period or a comma, this function will emit a bad_hdl error message.  HDL names are case-insensitive and can incorporate any printable Unicode characters so the test for endashes and terminal punctuation may not be technically correct but it appears, that in practice these characters are rarely if ever used in HDLs.  Query string parameters are named here: https://www.handle.net/proxy_servlet.html.  query strings are not displayed but since '?' is an allowed character in an HDL, '?' followed by one of the query parameters is the only way we have to detect the query string so that it isn't URL-encoded with the rest of the identifier.  ]]  local function hdl (options) 	local id = options.id; 	local access = options.access; 	local handler = options.handler; 	local query_params = {														-- list of known query parameters from https://www.handle.net/proxy_servlet.html 		'noredirect', 		'ignore_aliases', 		'auth', 		'cert', 		'index', 		'type', 		'urlappend', 		'locatt', 		'action', 		} 	 	local hdl, suffix, param = id:match ('(.-)(%?(%a+).+)$');					-- look for query string 	local found;  	if hdl then																	-- when there are query strings, this is the handle identifier portion 		for _, q in ipairs (query_params) do									-- spin through the list of query parameters 			if param:match ('^' .. q) then										-- if the query string begins with one of the parameters 				found = true;													-- announce a find 				break;															-- and stop looking 			end 		end 	end  	if found then 		id = hdl;																-- found so replace id with the handle portion; this will be URL-encoded, suffix will not 	else 		suffix = ;															-- make sure suffix is empty string for concatenation else 	end  	local text = external_link_id ({link = handler.link, label = handler.label, q = handler.q, redirect = handler.redirect, 			prefix = handler.prefix, id = id, suffix = suffix, separator = handler.separator, encode = handler.encode, access = access})  	if nil == id:match("^[^%s–]-/[^%s–]-[^%.,]$") then							-- HDL must contain a forward slash, must not contain spaces, endashes, and must not end with period or comma 		set_message ('err_bad_hdl' ); 		options.coins_list_t['HDL'] = nil;										-- when error, unset so not included in COinS 	end  	return text; end  --[[--------------------------< I S B N >----------------------------------------------------------------------  Determines whether an ISBN string is valid  ]]  local function isbn (options_t) 	local isbn_str = options_t.id; 	local ignore_invalid = options_t.accept; 	local handler = options_t.handler; 	local year = options_t.Year;												-- when set, valid anchor_year; may have a disambiguator which must be removed  	local function return_result (check, err_type)								-- local function to handle the various returns 		local ISBN = internal_link_id ({link = handler.link, label = handler.label, redirect = handler.redirect, 						prefix = handler.prefix, id = isbn_str, separator = handler.separator}); 		if ignore_invalid then													-- if ignoring ISBN errors 			set_message ('maint_isbn_ignore');									-- add a maint category even when there is no error 		else																	-- here when not ignoring 			if not check then													-- and there is an error 				options_t.coins_list_t['ISBN'] = nil;								-- when error, unset so not included in COinS 				set_message ('err_bad_isbn', err_type);							-- set an error message 				return ISBN;										 			-- return id text 			end 		end 		return ISBN;															-- return id text 	end  	if year and not ignore_invalid then											--  		year = year:match ('%d%d%d%d?');										-- strip disambiguator if present 		if year and (1965 > tonumber(year)) then 			set_message ('err_invalid_isbn_date');								-- set an error message 			return internal_link_id ({link = handler.link, label = handler.label, redirect = handler.redirect, 					prefix = handler.prefix, id = isbn_str, separator = handler.separator}); 		end 	end  	if nil ~= isbn_str:match ('[^%s-0-9X]') then 		return return_result (false, cfg.err_msg_supl.char);					-- fail if isbn_str contains anything but digits, hyphens, or the uppercase X 	end  	local id = isbn_str:gsub ('[%s-]', );										-- remove hyphens and whitespace  	local len = id:len();   	if len ~= 10 and len ~= 13 then 		return return_result (false, cfg.err_msg_supl.length);					-- fail if incorrect length 	end  	if len == 10 then 		if id:match ('^%d*X?$') == nil then										-- fail if isbn_str has 'X' anywhere but last position 			return return_result (false, cfg.err_msg_supl.form);									 		end 		if not is_valid_isxn (id, 10) then										-- test isbn-10 for numerical validity 			return return_result (false, cfg.err_msg_supl.check);				-- fail if isbn-10 is not numerically valid 		end 		if id:find ('^63[01]') then												-- 630xxxxxxx and 631xxxxxxx are (apparently) not valid isbn group ids but are used by amazon as numeric identifiers (asin) 			return return_result (false, cfg.err_msg_supl.group);				-- fail if isbn-10 begins with 630/1 		end 		return return_result (true, cfg.err_msg_supl.check);					-- pass if isbn-10 is numerically valid 	else 		if id:match ('^%d+$') == nil then 			return return_result (false, cfg.err_msg_supl.char);				-- fail if ISBN-13 is not all digits 		end 		if id:match ('^97[89]%d*$') == nil then 			return return_result (false, cfg.err_msg_supl.prefix);				-- fail when ISBN-13 does not begin with 978 or 979 		end 		if id:match ('^9790') then 			return return_result (false, cfg.err_msg_supl.group);				-- group identifier '0' is reserved to ISMN 		end 		return return_result (is_valid_isxn_13 (id), cfg.err_msg_supl.check); 	end end  --[[--------------------------< A S I N >----------------------------------------------------------------------  Formats a link to Amazon.  Do simple error checking: ASIN must be mix of 10 numeric or uppercase alpha characters.  If a mix, first character must be uppercase alpha; if all numeric, ASINs must be 10-digit ISBN. If 10-digit ISBN, add a maintenance category so a bot or AWB script can replace |asin= with |isbn=. Error message if not 10 characters, if not ISBN-10, if mixed and first character is a digit.  |asin=630....... and |asin=631....... are (apparently) not a legitimate ISBN though it checksums as one; these do not cause this function to emit the maint_asin message  This function is positioned here because it calls isbn()  ]]  local function asin (options) 	local id = options.id; 	local domain = options.ASINTLD; 	 	local err_flag;  	if not id:match("^[%d%u][%d%u][%d%u][%d%u][%d%u][%d%u][%d%u][%d%u][%d%u][%d%u]$") then 		err_flag = set_message ('err_bad_asin');								-- ASIN is not a mix of 10 uppercase alpha and numeric characters 	else 		if id:match("^%d%d%d%d%d%d%d%d%d[%dX]$") then							-- if 10-digit numeric (or 9 digits with terminal X) 			if is_valid_isxn (id, 10) then										-- see if ASIN value is or validates as ISBN-10 				if not id:find ('^63[01]') then									-- 630xxxxxxx and 631xxxxxxx are (apparently) not a valid isbn prefixes but are used by amazon as a numeric identifier 					err_flag = set_message ('err_bad_asin');					-- ASIN has ISBN-10 form but begins with something other than 630/1 so probably an isbn  				end 			elseif not is_set (err_flag) then 				err_flag = set_message ('err_bad_asin');						-- ASIN is not ISBN-10 			end 		elseif not id:match("^%u[%d%u]+$") then 			err_flag = set_message ('err_bad_asin');							-- asin doesn't begin with uppercase alpha 		end 	end 	if (not is_set (domain)) or in_array (domain, {'us'}) then					-- default: United States 		domain = "com"; 	elseif in_array (domain, {'jp', 'uk'}) then									-- Japan, United Kingdom 		domain = "co." .. domain; 	elseif in_array (domain, {'z.cn'}) then 									-- China 		domain = "cn"; 	elseif in_array (domain, {'au', 'br', 'mx', 'sg', 'tr'}) then				-- Australia, Brazil, Mexico, Singapore, Turkey 		domain = "com." .. domain; 	elseif not in_array (domain, {'ae', 'ca', 'cn', 'de', 'es', 'fr', 'in', 'it', 'nl', 'pl', 'sa', 'se', 'co.jp', 'co.uk', 'com', 'com.au', 'com.br', 'com.mx', 'com.sg', 'com.tr'}) then -- Arabic Emirates, Canada, China, Germany, Spain, France, Indonesia, Italy, Netherlands, Poland, Saudi Arabia, Sweden (as of 2021-03 Austria (.at), Liechtenstein (.li) and Switzerland (.ch) still redirect to the German site (.de) with special settings, so don't maintain local ASINs for them) 		err_flag = set_message ('err_bad_asin_tld');							-- unsupported asin-tld value 	end 	local handler = options.handler;  	if not is_set (err_flag) then 		options.coins_list_t['ASIN'] = handler.prefix .. domain .. "/dp/" .. id;	-- asin for coins 	else 		options.coins_list_t['ASIN'] = nil;										-- when error, unset so not included in COinS 	end 	 	return external_link_id ({link = handler.link, label = handler.label, q = handler.q, redirect = handler.redirect, 		prefix = handler.prefix .. domain .. "/dp/", 		id = id, encode = handler.encode, separator = handler.separator}) end  --[[--------------------------< I S M N >----------------------------------------------------------------------  Determines whether an ISMN string is valid.  Similar to ISBN-13, ISMN is 13 digits beginning 979-0-... and uses the same check digit calculations.  See https://www.ismn-international.org/download/Web_ISMN_Users_Manual_2008-6.pdf section 2, pages 9–12.  ismn value not made part of COinS metadata because we don't have a url or isn't a COinS-defined identifier (rft.xxx) or an identifier registered at info-uri.info (info:)  ]]  local function ismn (options) 	local id = options.id; 	local handler = options.handler; 	local text; 	local valid_ismn = true; 	local id_copy;  	id_copy = id;																-- save a copy because this testing is destructive 	id = id:gsub ('[%s-]', );													-- remove hyphens and white space  	if 13 ~= id:len() or id:match ("^9790%d*$" ) == nil then					-- ISMN must be 13 digits and begin with 9790 		valid_ismn = false; 	else 		valid_ismn=is_valid_isxn_13 (id);										-- validate ISMN 	end  	--	text = internal_link_id ({link = handler.link, label = handler.label, q = handler.q, redirect = handler.redirect,		-- use this (or external version) when there is some place to link to 	--		prefix = handler.prefix, id = id_copy, separator = handler.separator, encode = handler.encode})  	text = table.concat (														-- because no place to link to yet 		{ 		make_wikilink (link_label_make (handler), handler.label), 		handler.separator, 		id_copy 		});  	if false == valid_ismn then 		options.coins_list_t['ISMN'] = nil;										-- when error, unset so not included in COinS; not really necessary here because ismn not made part of COinS 		set_message ('err_bad_ismn');											-- create an error message if the ISMN is invalid 	end  	 	return text; end  --[[--------------------------< I S S N >----------------------------------------------------------------------  Validate and format an ISSN.  This code fixes the case where an editor has included an ISSN in the citation but has separated the two groups of four digits with a space.  When that condition occurred, the resulting link looked like this:  	|issn=0819 4327 gives: 4327 0819 4327	-- can't have spaces in an external link 	 This code now prevents that by inserting a hyphen at the ISSN midpoint.  It also validates the ISSN for length and makes sure that the checkdigit agrees with the calculated value.  Incorrect length (8 digits), characters other than 0-9 and X, or checkdigit / calculated value mismatch will all cause a check ISSN error message.  The ISSN is always displayed with a hyphen, even if the ISSN was given as a single group of 8 digits.  ]]  local function issn (options) 	local id = options.id; 	local handler = options.handler; 	local ignore_invalid = options.accept;  	local issn_copy = id;														-- save a copy of unadulterated ISSN; use this version for display if ISSN does not validate 	local text; 	local valid_issn = true;  	id = id:gsub ('[%s-]', );													-- remove hyphens and whitespace  	if 8 ~= id:len() or nil == id:match ("^%d*X?$" ) then						-- validate the ISSN: 8 digits long, containing only 0-9 or X in the last position 		valid_issn = false;														-- wrong length or improper character 	else 		valid_issn = is_valid_isxn (id, 8);										-- validate ISSN 	end  	if true == valid_issn then 		id = string.sub (id, 1, 4 ) .. "-" .. string.sub (id, 5 );				-- if valid, display correctly formatted version 	else 		id = issn_copy;															-- if not valid, show the invalid ISSN with error message 	end  	text = external_link_id ({link = handler.link, label = handler.label, q = handler.q, redirect = handler.redirect, 		prefix = handler.prefix, id = id, separator = handler.separator, encode = handler.encode})  	if ignore_invalid then 		set_message ('maint_issn_ignore'); 	else 		if false == valid_issn then 			options.coins_list_t['ISSN'] = nil;									-- when error, unset so not included in COinS 			set_message ('err_bad_issn', (options.hkey == 'EISSN') and 'e' or );	-- create an error message if the ISSN is invalid 		end  	end 	 	return text; end  --[[--------------------------< J F M >-----------------------------------------------------------------------  A numerical identifier in the form nn.nnnn.nn  ]]  local function jfm (options) 	local id = options.id; 	local handler = options.handler; 	local id_num;  	id_num = id:match ('^[Jj][Ff][Mm](.*)$');									-- identifier with jfm prefix; extract identifier  	if is_set (id_num) then 		set_message ('maint_jfm_format'); 	else																		-- plain number without JFM prefix 		id_num = id;															-- if here id does not have prefix 	end  	if id_num and id_num:match('^%d%d%.%d%d%d%d%.%d%d$') then 		id = id_num;															-- jfm matches pattern 	else 		set_message ('err_bad_jfm' );											-- set an error message 		options.coins_list_t['JFM'] = nil;										-- when error, unset so not included in COinS 	end 	 	return external_link_id ({link = handler.link, label = handler.label, q = handler.q, redirect = handler.redirect, 			prefix = handler.prefix, id = id, separator = handler.separator, encode = handler.encode}); end  --[[--------------------------< J S T O R >--------------------------------------------------------------------  Format a JSTOR with some error checking  ]]  local function jstor (options) 	local id = options.id; 	local access = options.access; 	local handler = options.handler;  	if id:find ('[Jj][Ss][Tt][Oo][Rr]') or id:find ('^https?://') or id:find ('%s') then 		set_message ('err_bad_jstor');											-- set an error message 		options.coins_list_t['JSTOR'] = nil;									-- when error, unset so not included in COinS 	end 	 	return external_link_id ({link = handler.link, label = handler.label, q = handler.q, redirect = handler.redirect, 		prefix = handler.prefix, id = id, separator = handler.separator, encode = handler.encode, access = access}); end  --[[--------------------------< L C C N >----------------------------------------------------------------------  Format LCCN link and do simple error checking.  LCCN is a character string 8-12 characters long. The length of the LCCN dictates the character type of the first 1-3 characters; the rightmost eight are always digits. https://oclc-research.github.io/infoURI-Frozen/info-uri.info/info:lccn/reg.html  length = 8 then all digits length = 9 then lccn[1] is lowercase alpha length = 10 then lccn[1] and lccn[2] are both lowercase alpha or both digits length = 11 then lccn[1] is lower case alpha, lccn[2] and lccn[3] are both lowercase alpha or both digits length = 12 then lccn[1] and lccn[2] are both lowercase alpha  ]]  local function lccn (options) 	local lccn = options.id; 	local handler = options.handler; 	local err_flag;																-- presume that LCCN is valid 	local id = lccn;															-- local copy of the LCCN  	id = normalize_lccn (id);													-- get canonical form (no whitespace, hyphens, forward slashes) 	local len = id:len();														-- get the length of the LCCN  	if 8 == len then 		if id:match("[^%d]") then												-- if LCCN has anything but digits (nil if only digits) 			err_flag = set_message ('err_bad_lccn');							-- set an error message 		end 	elseif 9 == len then														-- LCCN should be adddddddd 		if nil == id:match("%l%d%d%d%d%d%d%d%d") then							-- does it match our pattern? 			err_flag = set_message ('err_bad_lccn');							-- set an error message 		end 	elseif 10 == len then														-- LCCN should be aadddddddd or dddddddddd 		if id:match("[^%d]") then												-- if LCCN has anything but digits (nil if only digits) ... 			if nil == id:match("^%l%l%d%d%d%d%d%d%d%d") then					-- ... see if it matches our pattern 				err_flag = set_message ('err_bad_lccn');						-- no match, set an error message 			end 		end 	elseif 11 == len then														-- LCCN should be aaadddddddd or adddddddddd 		if not (id:match("^%l%l%l%d%d%d%d%d%d%d%d") or id:match("^%l%d%d%d%d%d%d%d%d%d%d")) then	-- see if it matches one of our patterns 			err_flag = set_message ('err_bad_lccn');							-- no match, set an error message 		end 	elseif 12 == len then														-- LCCN should be aadddddddddd 		if not id:match("^%l%l%d%d%d%d%d%d%d%d%d%d") then						-- see if it matches our pattern 			err_flag = set_message ('err_bad_lccn');							-- no match, set an error message 		end 	else 		err_flag = set_message ('err_bad_lccn');								-- wrong length, set an error message 	end  	if not is_set (err_flag) and nil ~= lccn:find ('%s') then 		err_flag = set_message ('err_bad_lccn');								-- lccn contains a space, set an error message 	end  	if is_set (err_flag) then 		options.coins_list_t['LCCN'] = nil;										-- when error, unset so not included in COinS 	end  	return external_link_id ({link = handler.link, label = handler.label, q = handler.q, redirect = handler.redirect, 			prefix = handler.prefix, id = lccn, separator = handler.separator, encode = handler.encode}); end  --[[--------------------------< M E D R X I V >-----------------------------------------------------------------  Format medRxiv ID and do simple error checking.  Similar to later bioRxiv IDs, medRxiv IDs are prefixed with a yyyy.mm.dd. date and suffixed with an optional version identifier.  Ealiest date accepted is 2020.01.01  The medRxiv ID is a date followed by an eight-digit number followed by an optional version indicator 'v' and one or more digits: 	https://www.medrxiv.org/content/10.1101/2020.11.16.20232009v2 -> 10.1101/2020.11.16.20232009v2  ]]  local function medrxiv (options) 	local id = options.id; 	local handler = options.handler; 	local err_msg_flag = true;													-- flag; assume that there will be an error  	local patterns = { 		'%d%d%d%d%d%d%d%d$',													-- simple 8-digit identifier; these should be relatively rare 		'^10%.1101/(20%d%d)%.(%d%d)%.(%d%d)%.%d%d%d%d%d%d%d%dv%d+$',			-- y.m.d. date + 8-digit identifier + version (2020-01-01 and later) 		'^10%.1101/(20%d%d)%.(%d%d)%.(%d%d)%.%d%d%d%d%d%d%d%d$',				-- y.m.d. date + 8-digit identifier (2020-01-01 and later) 		} 	 	for _, pattern in ipairs (patterns) do										-- spin through the patterns looking for a match 		if id:match (pattern) then 			local y, m, d = id:match (pattern);									-- found a match, attempt to get year, month and date from the identifier  			if m then															-- m is nil when id is the 8-digit form 				if not is_valid_rxiv_date (y, m, d, 'b') then					-- validate the encoded date; 'b' for medrxiv limit 					break;														-- date fail; break out early so we don't unset the error message 				end 			end 			err_msg_flag = nil;													-- we found a match so unset the error message 			break;																-- and done 		end 	end																			-- <err_msg_flag> remains set here when no match  	if err_msg_flag then 		options.coins_list_t['MEDRXIV'] = nil;									-- when error, unset so not included in COinS 		set_message ('err_bad_medrxiv');										-- and set the error message 	end 	 	return external_link_id ({link = handler.link, label = handler.label, q = handler.q, redirect = handler.redirect, 			prefix = handler.prefix, id = id, separator = handler.separator, 			encode = handler.encode, access = handler.access}); end  --[[--------------------------< M R >--------------------------------------------------------------------------  A seven digit number; if not seven digits, zero-fill leading digits to make seven digits.  ]]  local function mr (options) 	local id = options.id; 	local handler = options.handler; 	local id_num; 	local id_len;  	id_num = id:match ('^[Mm][Rr](%d+)$');										-- identifier with mr prefix  	if is_set (id_num) then 		set_message ('maint_mr_format');										-- add maint cat 	else																		-- plain number without mr prefix 		id_num = id:match ('^%d+$');											-- if here id is all digits 	end  	id_len = id_num and id_num:len() or 0; 	if (7 >= id_len) and (0 ~= id_len) then 		id = string.rep ('0', 7-id_len) .. id_num;								-- zero-fill leading digits 	else 		set_message ('err_bad_mr');												-- set an error message 		options.coins_list_t['MR'] = nil;										-- when error, unset so not included in COinS 	end 	 	return external_link_id ({link = handler.link, label = handler.label, q = handler.q, redirect = handler.redirect, 			prefix = handler.prefix, id = id, separator = handler.separator, encode = handler.encode}); end  --[[--------------------------< O C L C >----------------------------------------------------------------------  Validate and format an OCLC ID.  https://www.oclc.org/batchload/controlnumber.en.html  archived at: https://web.archive.org/web/20161228233804/https://www.oclc.org/batchload/controlnumber.en.html  ]]  local function oclc (options) 	local id = options.id; 	local handler = options.handler; 	local number;  	if id:match('^ocm%d%d%d%d%d%d%d%d$') then									-- ocm prefix and 8 digits; 001 field (12 characters) 		number = id:match('ocm(%d+)');											-- get the number 	elseif id:match('^ocn%d%d%d%d%d%d%d%d%d$') then								-- ocn prefix and 9 digits; 001 field (12 characters) 		number = id:match('ocn(%d+)');											-- get the number 	elseif id:match('^on%d%d%d%d%d%d%d%d%d%d+$') then							-- on prefix and 10 or more digits; 001 field (12 characters) 		number = id:match('^on(%d%d%d%d%d%d%d%d%d%d+)$');						-- get the number 	elseif id:match('^%(OCoLC%)[1-9]%d*$') then									-- (OCoLC) prefix and variable number digits; no leading zeros; 035 field 		number = id:match('%(OCoLC%)([1-9]%d*)');								-- get the number 		if 9 < number:len() then 			number = nil;														-- constrain to 1 to 9 digits; change this when OCLC issues 10-digit numbers 		end 	elseif id:match('^%d+$') then												-- no prefix 		number = id;															-- get the number 		if tonumber (id) > handler.id_limit then 			number = nil;														-- unset when id value exceeds the limit 		end 	end  	if number then																-- proper format 		id = number;															-- exclude prefix, if any, from external link 	else 		set_message ('err_bad_oclc')											-- add an error message if the id is malformed 		options.coins_list_t['OCLC'] = nil;										-- when error, unset so not included in COinS 	end 	 	return external_link_id ({link = handler.link, label = handler.label, q = handler.q, redirect = handler.redirect, 		prefix = handler.prefix, id = id, separator = handler.separator, encode = handler.encode}); end  --[[--------------------------< O P E N L I B R A R Y >--------------------------------------------------------  Formats an OpenLibrary link, and checks for associated errors.  ]]  local function openlibrary (options) 	local id = options.id; 	local access = options.access; 	local handler = options.handler; 	local ident, code = id:gsub('^OL', ):match("^(%d+([AMW]))$");				-- strip optional OL prefix followed immediately by digits followed by 'A', 'M', or 'W'; 	local err_flag; 	local prefix = {															-- these are appended to the handler.prefix according to code 		['A']='authors/OL', 		['M']='books/OL', 		['W']='works/OL', 		['X']='OL'																-- not a code; spoof when 'code' in id is invalid 		};  	if not ident then 		code = 'X';																-- no code or id completely invalid 		ident = id;																-- copy id to ident so that we display the flawed identifier 		err_flag = set_message ('err_bad_ol'); 	end  	if not is_set (err_flag) then 		options.coins_list_t['OL'] = handler.prefix .. prefix[code] .. ident;	-- experiment for ol coins 	else 		options.coins_list_t['OL'] = nil;										-- when error, unset so not included in COinS 	end  	return external_link_id ({link = handler.link, label = handler.label, q = handler.q, redirect = handler.redirect, 		prefix = handler.prefix .. prefix[code], 		id = ident, separator = handler.separator, encode = handler.encode, 		access = access}); end  --[[--------------------------< O S T I >----------------------------------------------------------------------  Format OSTI and do simple error checking. OSTIs are sequential numbers beginning at 1 and counting up.  This code checks the OSTI to see that it contains only digits and is less than test_limit specified in the configuration; the value in test_limit will need to be updated periodically as more OSTIs are issued.  NB. 1018 is the lowest OSTI number found in the wild (so far) and resolving OK on the OSTI site  ]]  local function osti (options) 	local id = options.id; 	local access = options.access; 	local handler = options.handler;  	if id:match("[^%d]") then													-- if OSTI has anything but digits 		set_message ('err_bad_osti');											-- set an error message 		options.coins_list_t['OSTI'] = nil;										-- when error, unset so not included in COinS 	else																		-- OSTI is only digits 		local id_num = tonumber (id);											-- convert id to a number for range testing 		if 1018 > id_num or handler.id_limit < id_num then						-- if OSTI is outside test limit boundaries 			set_message ('err_bad_osti');										-- set an error message 			options.coins_list_t['OSTI'] = nil;									-- when error, unset so not included in COinS 		end 	end 	 	return external_link_id ({link = handler.link, label = handler.label, q = handler.q, redirect = handler.redirect, 			prefix = handler.prefix, id = id, separator = handler.separator, encode = handler.encode, access = access}); end  --[[--------------------------< P M C >------------------------------------------------------------------------  Format a PMC, do simple error checking, and check for embargoed articles.  The embargo parameter takes a date for a value. If the embargo date is in the future the PMC identifier will not be linked to the article.  If the embargo date is today or in the past, or if it is empty or omitted, then the PMC identifier is linked to the article through the link at cfg.id_handlers['PMC'].prefix.  PMC embargo date testing is done in function is_embargoed () which is called earlier because when the citation has |pmc=<value> but does not have a |url= then |title= is linked with the PMC link.  Function is_embargoed () returns the embargo date if the PMC article is still embargoed, otherwise it returns an empty string.  PMCs are sequential numbers beginning at 1 and counting up.  This code checks the PMC to see that it contains only digits and is less than test_limit; the value in local variable test_limit will need to be updated periodically as more PMCs are issued.  ]]  local function pmc (options) 	local id = options.id; 	local embargo = options.Embargo;											-- TODO: lowercase? 	local handler = options.handler; 	local err_flag; 	local id_num; 	local text;  	id_num = id:match ('^[Pp][Mm][Cc](%d+)$');									-- identifier with PMC prefix  	if is_set (id_num) then 		set_message ('maint_pmc_format'); 	else																		-- plain number without PMC prefix 		id_num = id:match ('^%d+$');											-- if here id is all digits 	end  	if is_set (id_num) then														-- id_num has a value so test it 		id_num = tonumber (id_num);												-- convert id_num to a number for range testing 		if 1 > id_num or handler.id_limit < id_num then							-- if PMC is outside test limit boundaries 			err_flag = set_message ('err_bad_pmc');								-- set an error message 		else 			id = tostring (id_num);												-- make sure id is a string 		end 	else																		-- when id format incorrect 		err_flag = set_message ('err_bad_pmc');									-- set an error message 	end 	 	if is_set (embargo) and is_set (is_embargoed (embargo)) then				-- is PMC is still embargoed? 		text = table.concat (													-- still embargoed so no external link 			{ 			make_wikilink (link_label_make (handler), handler.label), 			handler.separator, 			id, 			}); 	else 		text = external_link_id ({link = handler.link, label = handler.label, q = handler.q, redirect = handler.redirect,	-- no embargo date or embargo has expired, ok to link to article 			prefix = handler.prefix, id = id, separator = handler.separator, encode = handler.encode, access = handler.access, 			auto_link = not err_flag and 'pmc' or nil							-- do not auto-link when PMC has error 			}); 	end  	if err_flag then 		options.coins_list_t['PMC'] = nil;										-- when error, unset so not included in COinS 	end  	return text; end  --[[--------------------------< P M I D >----------------------------------------------------------------------  Format PMID and do simple error checking.  PMIDs are sequential numbers beginning at 1 and counting up.  This code checks the PMID to see that it contains only digits and is less than test_limit; the value in local variable test_limit will need to be updated periodically as more PMIDs are issued.  ]]  local function pmid (options) 	local id = options.id; 	local handler = options.handler;  	if id:match("[^%d]") then													-- if PMID has anything but digits 		set_message ('err_bad_pmid');											-- set an error message 		options.coins_list_t['PMID'] = nil;										-- when error, unset so not included in COinS 	else																		-- PMID is only digits 		local id_num = tonumber (id);											-- convert id to a number for range testing 		if 1 > id_num or handler.id_limit < id_num then							-- if PMID is outside test limit boundaries 			set_message ('err_bad_pmid');										-- set an error message 			options.coins_list_t['PMID'] = nil;									-- when error, unset so not included in COinS 		end 	end 	 	return external_link_id ({link = handler.link, label = handler.label, q = handler.q, redirect = handler.redirect, 			prefix = handler.prefix, id = id, separator = handler.separator, encode = handler.encode}); end  --[[--------------------------< R F C >------------------------------------------------------------------------  Format RFC and do simple error checking. RFCs are sequential numbers beginning at 1 and counting up.  This code checks the RFC to see that it contains only digits and is less than test_limit specified in the configuration; the value in test_limit will need to be updated periodically as more RFCs are issued.  An index of all RFCs is here: https://tools.ietf.org/rfc/  ]]  local function rfc (options) 	local id = options.id; 	local handler = options.handler;  	if id:match("[^%d]") then													-- if RFC has anything but digits 		set_message ('err_bad_rfc');											-- set an error message 		options.coins_list_t['RFC'] = nil;										-- when error, unset so not included in COinS 	else																		-- RFC is only digits 		local id_num = tonumber (id);											-- convert id to a number for range testing 		if 1 > id_num or handler.id_limit < id_num then							-- if RFC is outside test limit boundaries 			set_message ('err_bad_rfc');										-- set an error message 			options.coins_list_t['RFC'] = nil;									-- when error, unset so not included in COinS 		end 	end 	 	return external_link_id ({link = handler.link, label = handler.label, q = handler.q, redirect = handler.redirect, 			prefix = handler.prefix, id = id, separator = handler.separator, encode = handler.encode, access = handler.access}); end  --[[--------------------------< S 2 C I D >--------------------------------------------------------------------  Format an S2CID, do simple error checking  S2CIDs are sequential numbers beginning at 1 and counting up.  This code checks the S2CID to see that it is only digits and is less than test_limit; the value in local variable test_limit will need to be updated periodically as more S2CIDs are issued.  ]]  local function s2cid (options) 	local id = options.id; 	local access = options.access; 	local handler = options.handler; 	local id_num; 	local text; 	 	id_num = id:match ('^[1-9]%d*$');											-- id must be all digits; must not begin with 0; no open access flag   	if is_set (id_num) then														-- id_num has a value so test it 		id_num = tonumber (id_num);												-- convert id_num to a number for range testing 		if handler.id_limit < id_num then										-- if S2CID is outside test limit boundaries 			set_message ('err_bad_s2cid');										-- set an error message 			options.coins_list_t['S2CID'] = nil;								-- when error, unset so not included in COinS 		end 	else																		-- when id format incorrect 		set_message ('err_bad_s2cid');											-- set an error message 		options.coins_list_t['S2CID'] = nil;									-- when error, unset so not included in COinS 	end  	text = external_link_id ({link = handler.link, label = handler.label, q = handler.q, redirect = handler.redirect, 		prefix = handler.prefix, id = id, separator = handler.separator, encode = handler.encode, access = access});  	return text; end  --[[--------------------------< S B N >------------------------------------------------------------------------  9-digit form of ISBN-10; uses same check-digit validation when SBN is prefixed with an additional '0' to make 10 digits  sbn value not made part of COinS metadata because we don't have a url or isn't a COinS-defined identifier (rft.xxx) or an identifier registered at info-uri.info (info:)  ]]  local function sbn (options) 	local id = options.id; 	local ignore_invalid = options.accept; 	local handler = options.handler; 	local function return_result (check, err_type)								-- local function to handle the various returns 		local SBN = internal_link_id ({link = handler.link, label = handler.label, redirect = handler.redirect, 						prefix = handler.prefix, id = id, separator = handler.separator}); 		if not ignore_invalid then												-- if not ignoring SBN errors 			if not check then 				options.coins_list_t['SBN'] = nil;								-- when error, unset so not included in COinS; not really necessary here because sbn not made part of COinS 				set_message ('err_bad_sbn', {err_type});						-- display an error message 				return SBN;  			end 		else 			set_message ('maint_isbn_ignore');									-- add a maint category even when there is no error (ToDo: Possibly switch to separate message for SBNs only) 		end 		return SBN; 	end  	if id:match ('[^%s-0-9X]') then 		return return_result (false, cfg.err_msg_supl.char);					-- fail if SBN contains anything but digits, hyphens, or the uppercase X 	end  	local ident = id:gsub ('[%s-]', '');										-- remove hyphens and whitespace; they interfere with the rest of the tests  	if  9 ~= ident:len() then 		return return_result (false, cfg.err_msg_supl.length);					-- fail if incorrect length 	end  	if ident:match ('^%d*X?$') == nil then 		return return_result (false, cfg.err_msg_supl.form);					-- fail if SBN has 'X' anywhere but last position 	end  	return return_result (is_valid_isxn ('0' .. ident, 10), cfg.err_msg_supl.check); end  --[[--------------------------< S S R N >----------------------------------------------------------------------  Format an SSRN, do simple error checking  SSRNs are sequential numbers beginning at 100? and counting up.  This code checks the SSRN to see that it is only digits and is greater than 99 and less than test_limit; the value in local variable test_limit will need to be updated periodically as more SSRNs are issued.  ]]  local function ssrn (options) 	local id = options.id; 	local handler = options.handler; 	local id_num; 	local text; 	 	id_num = id:match ('^%d+$');												-- id must be all digits  	if is_set (id_num) then														-- id_num has a value so test it 		id_num = tonumber (id_num);												-- convert id_num to a number for range testing 		if 100 > id_num or handler.id_limit < id_num then						-- if SSRN is outside test limit boundaries 			set_message ('err_bad_ssrn');										-- set an error message 			options.coins_list_t['SSRN'] = nil;									-- when error, unset so not included in COinS 		end 	else																		-- when id format incorrect 		set_message ('err_bad_ssrn');											-- set an error message 		options.coins_list_t['SSRN'] = nil;										-- when error, unset so not included in COinS 	end 	 	text = external_link_id ({link = handler.link, label = handler.label, q = handler.q, redirect = handler.redirect, 		prefix = handler.prefix, id = id, separator = handler.separator, encode = handler.encode, access = options.access});  	return text; end  --[[--------------------------< U S E N E T _ I D >------------------------------------------------------------  Validate and format a usenet message id.  Simple error checking, looks for 'id-left@id-right' not enclosed in '<' and/or '>' angle brackets.  ]]  local function usenet_id (options) 	local id = options.id; 	local handler = options.handler;  	local text = external_link_id ({link = handler.link, label = handler.label, q = handler.q, redirect = handler.redirect, 		prefix = handler.prefix, id = id, separator = handler.separator, encode = handler.encode})   	if not id:match('^.+@.+$') or not id:match('^[^<].*[^>]$') then				-- doesn't have '@' or has one or first or last character is '< or '>' 		set_message ('err_bad_usenet_id')										-- add an error message if the message id is invalid 		options.coins_list_t['USENETID'] = nil;									-- when error, unset so not included in COinS 	end  	 	return text; end  --[[--------------------------< Z B L >-----------------------------------------------------------------------  A numerical identifier in the form nnnn.nnnnn - leading zeros in the first quartet optional  format described here: http://emis.mi.sanu.ac.rs/ZMATH/zmath/en/help/search/  temporary format is apparently eight digits.  Anything else is an error  ]]  local function zbl (options) 	local id = options.id; 	local handler = options.handler;  	if id:match('^%d%d%d%d%d%d%d%d$') then										-- is this identifier using temporary format? 		set_message ('maint_zbl');												-- yes, add maint cat 	elseif not id:match('^%d?%d?%d?%d%.%d%d%d%d%d$') then						-- not temporary, is it normal format? 		set_message ('err_bad_zbl');											-- no, set an error message 		options.coins_list_t['ZBL'] = nil;										-- when error, unset so not included in COinS 	end 	 	return external_link_id ({link = handler.link, label = handler.label, q = handler.q, redirect = handler.redirect, 			prefix = handler.prefix, id = id, separator = handler.separator, encode = handler.encode}); end  --============================<< I N T E R F A C E   F U N C T I O N S >>==========================================  --[[--------------------------< E X T R A C T _ I D S >------------------------------------------------------------  Populates ID table from arguments using configuration settings. Loops through cfg.id_handlers and searches args for any of the parameters listed in each cfg.id_handlers['...'].parameters.  If found, adds the parameter and value to the identifier list.  Emits redundant error message if more than one alias exists in args  ]]  local function extract_ids (args) 	local id_list = {};															-- list of identifiers found in args 	for k, v in pairs (cfg.id_handlers) do										-- k is uppercase identifier name as index to cfg.id_handlers; e.g. cfg.id_handlers['ISBN'], v is a table 		v = select_one (args, v.parameters, 'err_redundant_parameters' );		-- v.parameters is a table of aliases for k; here we pick one from args if present 		if is_set (v) then id_list[k] = v; end									-- if found in args, add identifier to our list 	end 	return id_list; end  --[[--------------------------< E X T R A C T _ I D _ A C C E S S _ L E V E L S >--------------------------------------  Fetches custom id access levels from arguments using configuration settings. Parameters which have a predefined access level (e.g. arxiv) do not use this function as they are directly rendered as free without using an additional parameter.  returns a table of k/v pairs where k is same as the identifier's key in cfg.id_handlers and v is the assigned (valid) keyword  access-level values must match the case used in cfg.keywords_lists['id-access'] (lowercase unless there is some special reason for something else)  ]]  local function extract_id_access_levels (args, id_list) 	local id_accesses_list = {}; 	for k, v in pairs (cfg.id_handlers) do 		local access_param = v.custom_access;									-- name of identifier's access-level parameter 		if is_set (access_param) then 			local access_level = args[access_param];							-- get the assigned value if there is one 			if is_set (access_level) then 				if not in_array (access_level, cfg.keywords_lists['id-access']) then	-- exact match required 					set_message ('err_invalid_param_val', {access_param, access_level});	 					access_level = nil;											-- invalid so unset 				end 				if not is_set (id_list[k]) then									-- identifier access-level must have a matching identifier 					set_message ('err_param_access_requires_param', {k:lower()});	-- parameter name is uppercase in cfg.id_handlers (k); lowercase for error message 				end 				id_accesses_list[k] = cfg.keywords_xlate[access_level];			-- get translated keyword 			end 		end 	end 	return id_accesses_list; end  --[[--------------------------< B U I L D _ I D _ L I S T >----------------------------------------------------  render the identifiers into a sorted sequence table  <ID_list_coins_t> is a table of k/v pairs where k is same as key in cfg.id_handlers and v is the assigned value <options_t> is a table of various k/v option pairs provided in the call to new_build_id_list(); 	modified by	this function and passed to all identifier rendering functions <access_levels_t> is a table of k/v pairs where k is same as key in cfg.id_handlers and v is the assigned value (if valid)  returns a sequence table of sorted (by hkey - 'handler' key) rendered identifier strings  ]]  local function build_id_list (ID_list_coins_t, options_t, access_levels_t) 	local ID_list_t = {}; 	local accept; 	local func_map = {															--function map points to functions associated with hkey identifier 		['ARXIV'] = arxiv, 		['ASIN'] = asin, 		['BIBCODE'] = bibcode, 		['BIORXIV'] = biorxiv, 		['CITESEERX'] = citeseerx, 		['DOI'] = doi, 		['EISSN'] = issn, 		['HDL'] = hdl, 		['ISBN'] = isbn, 		['ISMN'] = ismn, 		['ISSN'] = issn, 		['JFM'] = jfm, 		['JSTOR'] = jstor, 		['LCCN'] = lccn, 		['MEDRXIV'] = medrxiv, 		['MR'] = mr, 		['OCLC'] = oclc, 		['OL'] = openlibrary, 		['OSTI'] = osti, 		['PMC'] = pmc, 		['PMID'] = pmid, 		['RFC']  = rfc, 		['S2CID'] = s2cid, 		['SBN'] = sbn, 		['SSRN'] = ssrn, 		['USENETID'] = usenet_id, 		['ZBL'] = zbl, 		}  	for hkey, v in pairs (ID_list_coins_t) do 		v, accept = has_accept_as_written (v);									-- remove accept-as-written markup if present; accept is boolean true when markup removed; false else 																				-- every function gets the options table with value v and accept boolean 		options_t.hkey = hkey;													-- ~/Configuration handler key 		options_t.id = v;														-- add that identifier value to the options table 		options_t.accept = accept;												-- add the accept boolean flag 		options_t.access = access_levels_t[hkey];								-- add the access level for those that have an |<identifier-access= parameter 		options_t.handler = cfg.id_handlers[hkey]; 		options_t.coins_list_t = ID_list_coins_t;								-- pointer to ID_list_coins_t; for |asin= and |ol=; also to keep erroneous values out of the citation's metadata 		options_t.coins_list_t[hkey] = v;										-- id value without accept-as-written markup for metadata 		 		if options_t.handler.access and not in_array (options_t.handler.access, cfg.keywords_lists['id-access']) then 			error (cfg.messages['unknown_ID_access'] .. options_t.handler.access);	-- here when handler access key set to a value not listed in list of allowed id access keywords 		end  		if func_map[hkey] then 			local id_text = func_map[hkey] (options_t);							-- call the function to get identifier text and any error message 			table.insert (ID_list_t, {hkey, id_text});							-- add identifier text to the output sequence table 		else 			error (cfg.messages['unknown_ID_key'] .. hkey);						-- here when func_map doesn't have a function for hkey 		end 	end  	local function comp (a, b)													-- used by following table.sort() 		return a[1]:lower() < b[1]:lower();										-- sort by hkey 	end  	table.sort (ID_list_t, comp);												-- sequence table of tables sort	 	for k, v in ipairs (ID_list_t) do											-- convert sequence table of tables to simple sequence table of strings 		ID_list_t[k] = v[2];													-- v[2] is the identifier rendering from the call to the various functions in func_map{} 	end 	 	return ID_list_t; end  --[[--------------------------< O P T I O N S _ C H E C K >----------------------------------------------------  check that certain option parameters have their associated identifier parameters with values  <ID_list_coins_t> is a table of k/v pairs where k is same as key in cfg.id_handlers and v is the assigned value <ID_support_t> is a sequence table of tables created in citation0() where each subtable has four elements: 	[1] is the support parameter's assigned value; empty string if not set 	[2] is a text string same as key in cfg.id_handlers 	[3] is cfg.error_conditions key used to create error message 	[4] is original ID support parameter name used to create error message 	 returns nothing; on error emits an appropriate error message  ]]  local function options_check (ID_list_coins_t, ID_support_t) 	for _, v in ipairs (ID_support_t) do 		if is_set (v[1]) and not ID_list_coins_t[v[2]] then						-- when support parameter has a value but matching identifier parameter is missing or empty 			set_message (v[3], (v[4]));											-- emit the appropriate error message 		end 	end end  --[[--------------------------< I D E N T I F I E R _ L I S T S _ G E T >--------------------------------------  Creates two identifier lists: a k/v table of identifiers and their values to be used locally and for use in the COinS metadata, and a sequence table of the rendered identifier strings that will be included in the rendered citation.  ]]  local function identifier_lists_get (args_t, options_t, ID_support_t) 	local ID_list_coins_t = extract_ids (args_t);										-- get a table of identifiers and their values for use locally and for use in COinS 	options_check (ID_list_coins_t, ID_support_t);										-- ID support parameters must have matching identifier parameters  	local ID_access_levels_t = extract_id_access_levels (args_t, ID_list_coins_t);		-- get a table of identifier access levels 	local ID_list_t = build_id_list (ID_list_coins_t, options_t, ID_access_levels_t);	-- get a sequence table of rendered identifier strings  	return ID_list_t, ID_list_coins_t;											-- return the tables end  --[[--------------------------< S E T _ S E L E C T E D _ M O D U L E S >--------------------------------------  Sets local cfg table and imported functions table to same (live or sandbox) as that used by the other modules.  ]]  local function set_selected_modules (cfg_table_ptr, utilities_page_ptr) 	cfg = cfg_table_ptr;  	has_accept_as_written = utilities_page_ptr.has_accept_as_written;			-- import functions from select Module:Citation/CS1/Utilities module 	is_set = utilities_page_ptr.is_set;								 	in_array = utilities_page_ptr.in_array; 	set_message = utilities_page_ptr.set_message; 	select_one = utilities_page_ptr.select_one; 	substitute = utilities_page_ptr.substitute; 	make_wikilink = utilities_page_ptr.make_wikilink;  	z = utilities_page_ptr.z;													-- table of tables in Module:Citation/CS1/Utilities end  --[[--------------------------< E X P O R T E D   F U N C T I O N S >------------------------------------------ ]]  return { 	auto_link_urls = auto_link_urls,											-- table of identifier URLs to be used when auto-linking |title= 	 	identifier_lists_get = identifier_lists_get,								-- experiment to replace individual calls to build_id_list(), extract_ids, extract_id_access_levels 	is_embargoed = is_embargoed; 	set_selected_modules = set_selected_modules; 	}