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--[[--------------------------< F O R W A R D   D E C L A R A T I O N S >--------------------------------------]]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/Utilitieslocal 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 elsefor identifiers that do not have q, returns nilfor 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 elseend--[[--------------------------< 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 Wikidatareturns 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 '&nbsp;',		ext_link		});end--[[--------------------------< I N T E R N A L _ L I N K _ I D >----------------------------------------------Formats a wiki-style internal linkTODO: 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 '&nbsp;',											-- add the separator		make_wikilink (			table.concat (				{				options.prefix,				id,																-- translated to Western digits				options.suffix or ''				}),			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= againsttoday's date.  If embargo date is in the future, returns the content of |pmc-embargo-date=; otherwise, returnsan 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 stringend--[=[-------------------------< 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 daysfor 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 {{#time:U|2019-12-11}} = 1576022400The medrxiv identifier has a start date of 2020-01-01.  The Unix timestamp for that date is {{#time:U|2020-01-01}} = 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 tomorrowinputs:	<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 dateend--[[--------------------------< 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 lengthand 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 zeroend--[[--------------------------< 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 lengthand 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 correctend--[[--------------------------< 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_identifierformat 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 spacesthe 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, ' [[https://arxiv.org/archive/', 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#bibcodesBut, this: 2015arXiv151206696F is apparently valid so apparently, the only things that really matter are length, 19 charactersand 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 exactly6 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 -> 10.1101/078733or 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 registrantThis function checks a DOI name for: prefix/suffix.  If the DOI name contains spaces or endashes, or, if it endswith 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 rarelyif ever used in DOI names.https://www.doi.org/doi_handbook/2_Numbering.html				-- 2.2 Syntax of a DOI namehttps://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 registrantThis function checks a HDL name for: prefix/suffix.  If the HDL name contains spaces, endashes, or, if it endswith 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 andterminal punctuation may not be technically correct but it appears, that in practice these characters are rarelyif ever used in HDLs.Query string parameters are named here: https://www.handle.net/proxy_servlet.html.  query strings are not displayedbut since '?' is an allowed character in an HDL, '?' followed by one of the query parameters is the only way wehave 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 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);	endend--[[--------------------------< A S I N >----------------------------------------------------------------------Formats a link to Amazon.  Do simple error checking: ASIN must be mix of 10 numeric or uppercase alphacharacters.  If a mix, first character must be uppercase alpha; if all numeric, ASINs must be 10-digitISBN. 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; thesedo not cause this function to emit the maint_asin messageThis 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 thesame check digit calculations.  See https://www.ismn-international.org/download/Web_ISMN_Users_Manual_2008-6.pdfsection 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 buthas separated the two groups of four digits with a space.  When that condition occurred, the resulting link lookedlike this:	|issn=0819 4327 gives: [https://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 lengthand makes sure that the checkdigit agrees with the calculated value.  Incorrect length (8 digits), charactersother than 0-9 and X, or checkdigit / calculated value mismatch will all cause a check ISSN error message.  TheISSN 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 ofthe 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.htmllength = 8 then all digitslength = 9 then lccn[1] is lowercase alphalength = 10 then lccn[1] and lccn[2] are both lowercase alpha or both digitslength = 11 then lccn[1] is lower case alpha, lccn[2] and lccn[3] are both lowercase alpha or both digitslength = 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 ayyyy.mm.dd. date and suffixed with an optional version identifier.  Ealiest date accepted is 2020.01.01The 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 {{dead link}}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.  Thiscode 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 notbe linked to the article.  If the embargo date is today or in the past, or if it is empty or omitted, then thePMC 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 citationhas |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 lessthan 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.  Thiscode checks the PMID to see that it contains only digits and is less than test_limit; the value in local variabletest_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.  Thiscode 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 checkingS2CIDs are sequential numbers beginning at 1 and counting up.  This code checks the S2CID to see that it is onlydigits and is less than test_limit; the value in local variable test_limit will need to be updated periodicallyas 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 digitssbn 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?$') == nil then		return return_result (false, cfg.err_msg_supl.form);					-- fail if SBN has 'X' anywhere but last position	end	return return_result (is_valid_isxn ('0' .. ident, 10), cfg.err_msg_supl.check);end--[[--------------------------< S S R N >----------------------------------------------------------------------Format an SSRN, do simple error checkingSSRNs are sequential numbers beginning at 100? and counting up.  This code checks the SSRN to see that it isonly digits and is greater than 99 and less than test_limit; the value in local variable test_limit will needto be updated periodically as more SSRNs are issued.]]local function ssrn (options)	local id = options.id;	local handler = options.handler;	local id_num;	local text;		id_num = id:match ('^%d+$');												-- 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 optionalformat 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 forany of the parameters listed in each cfg.id_handlers['...'].parameters.  If found, adds the parameter and value tothe 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 accesslevel (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) keywordaccess-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	endend--[[--------------------------< 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 theCOinS metadata, and a sequence table of the rendered identifier strings that will be included in the renderedcitation.]]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 tablesend--[[--------------------------< 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/Utilitiesend--[[--------------------------< 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;	}