--[[--------------------------< F O R W A R D D E C L A R A T I O N S >-------------------------------------- ]]  local is_set, in_array, set_error, select_one, add_maint_cat, substitute, make_wikilink; -- functions in Module:Citation/CS1/Utilities  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   --============================<< 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   --[[--------------------------< 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 );  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   if not (cfg.use_identifier_redirects and is_set (options.redirect)) then -- redirect has priority so if enabled and available don't fetch from wikidata because expensive  wd_article = wikidata_article_name_get (options.q); -- if wikidata has an article title for this wiki, get it;  end   local label_link = (cfg.use_identifier_redirects and is_set (options.redirect) and options.redirect) or wd_article or options.link;   return table.concat ({  make_wikilink (label_link, 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 link  ]]  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   if not (cfg.use_identifier_redirects and is_set (options.redirect)) then -- redirect has priority so if enabled and available don't fetch from wikidata because expensive  wd_article = wikidata_article_name_get (options.q); -- if wikidata has an article title for this wiki, get it;  end   local label_link = (cfg.use_identifier_redirects and is_set (options.redirect) and options.redirect) or wd_article or options.link;   return table.concat (  {  make_wikilink (label_link, 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 Latn 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 |embargo= against today's date. If embargo date is in the future, returns the content of |embargo=; otherwise, returns and empty string because the embargo has expired or because |embargo= was not set in this cite.  ]]  local function is_embargoed (embargo)  if is_set (embargo) then  local lang = mw.getContentLanguage();  local good1, embargo_date, good2, todays_date;  good1, embargo_date = pcall( lang.formatDate, lang, 'U', embargo );  good2, todays_date = pcall( lang.formatDate, lang, 'U' );   if good1 and good2 then -- if embargo date and today's date are good dates  if tonumber( embargo_date ) >= tonumber( todays_date ) then -- is embargo date is in the future?  return embargo; -- still embargoed  else  add_maint_cat ('embargo')  return ''; -- unset because embargo has expired  end  end  end  return ''; -- |embargo= not set return empty string end   --[=[-------------------------< I S _ V A L I D _ B I O R X I V _ D A T E >------------------------------------  returns true if:  2019-12-11T00:00Z <= biorxiv_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}} = 1576022400  biorxiv_date is the date provided in those |biorxiv= parameter values that are dated at time 00:00:00 UTC today is the current date at time 00:00:00 UTC plus 48 hours  if today is 2015-01-01T00:00:00 then  adding 24 hours gives 2015-01-02T00:00:00 – one second more than today  adding 24 hours gives 2015-01-03T00:00:00 – one second more than tomorrow  This function does not work if it is fed month names for languages other than English. Wikimedia #time: parser apparently doesn't understand non-Engish date month names. This function will always return false when the date contains a non-English month name because good1 is false after the call to lang.formatDate(). To get around that call this function with YYYY-MM-DD format dates.  ]=]  local function is_valid_biorxiv_date (biorxiv_date)  local good1, good2;  local biorxiv_ts, tomorrow_ts; -- to hold unix time stamps representing the dates  local lang_object = mw.getContentLanguage();   good1, biorxiv_ts = pcall (lang_object.formatDate, lang_object, 'U', biorxiv_date ); -- convert biorxiv_date value to unix timesatmp   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 which tonumber() may not understand  biorxiv_ts = tonumber (biorxiv_ts) or lang_object:parseFormattedNumber (biorxiv_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 time stamp  end   return ((1576022400 <= biorxiv_ts) and (biorxiv_ts < tomorrow_ts)) -- 2012-12-11T00:00Z <= biorxiv_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, issbn/issn must be checked for length and stripped of dashes, spaces and other non-isxn characters.  ]]  local function is_valid_isxn (isxn_str, len)  local temp = 0;  isxn_str = { isxn_str:byte(1, len) }; -- make a table of byte values '0' → 0x30 .. '9' → 0x39, 'X' → 0x58  len = len+1; -- adjust to be a loop counter  for i, v in ipairs( isxn_str ) do -- loop through all of the bytes and calculate the checksum  if v == string.byte( "X" ) then -- if checkdigit is X (compares the byte value of 'X' which is 0x58)  temp = temp + 10*( len - i ); -- it represents 10 decimal  else  temp = temp + tonumber( string.char(v) )*(len-i);  end  end  return temp % 11 == 0; -- returns true if calculation result is zero end   --[[--------------------------< IS _ V A L I D _ I S X N _ 1 3 >-----------------------------------------------  ISBN-13 and ISMN validator code calculates checksum across all 13 isbn/ismn digits including the check digit. If the number is valid, the result will be 0. Before calling this function, isbn-13/ismn must be checked for length and stripped of dashes, spaces and other non-isxn-13 characters.  ]]  local function is_valid_isxn_13 (isxn_str)  local temp=0;   isxn_str = { isxn_str:byte(1, 13) }; -- make a table of byte values '0' → 0x30 .. '9' → 0x39  for i, v in ipairs( isxn_str ) do  temp = temp + (3 - 2*(i % 2)) * tonumber( string.char(v) ); -- multiply odd index digits by 1, even index digits by 3 and sum; includes check digit  end  return temp % 10 == 0; -- sum modulo 10 is zero when isbn-13/ismn is correct end   --[[--------------------------< N O R M A L I Z E _ L C C N >--------------------------------------------------  lccn normalization (http://www.loc.gov/marc/lccn-namespace.html#normalization) 1. Remove all blanks. 2. If there is a forward slash (/) in the string, remove it, and remove all characters to the right of the forward slash. 3. If there is a hyphen in the string:  a. Remove it.  b. Inspect the substring following (to the right of) the (removed) hyphen. Then (and assuming that steps 1 and 2 have been carried out):  1. All these characters should be digits, and there should be six or less. (not done in this function)  2. If the length of the substring is less than 6, left-fill the substring with zeroes until the length is six.  Returns a normalized lccn for lccn() to validate. There is no error checking (step 3.b.1) performed in this function. ]]  local function normalize_lccn (lccn)  lccn = lccn:gsub ("%s", ""); -- 1. strip whitespace   if nil ~= string.find (lccn,'/') then  lccn = lccn:match ("(.-)/"); -- 2. remove forward slash and all character to the right of it  end   local prefix  local suffix  prefix, suffix = lccn:match ("(.+)%-(.+)"); -- 3.a remove hyphen by splitting the string into prefix and suffix   if nil ~= suffix then -- if there was a hyphen  suffix=string.rep("0", 6-string.len (suffix)) .. suffix; -- 3.b.2 left fill the suffix with 0s if suffix length less than 6  lccn=prefix..suffix; -- reassemble the lccn  end   return lccn;  end  --============================<< 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: http://arxiv.org/help/arxiv_identifier  format and error check arXiv identifier. There are three valid forms of the identifier: the first form, valid only between date codes 9108 and 0703 is:  arXiv:<archive>.<class>/<date code><number><version> where:  <archive> is a string of alpha characters - may be hyphenated; no other punctuation  <class> is a string of alpha characters - may be hyphenated; no other punctuation; 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 (id, class)  local handler = cfg.id_handlers['ARXIV'];  local year, month, version;  local err_cat = 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 9108-0703 format w/ & w/o version  year, month = id:match("^%a[%a%.%-]+/([90]%d)([01]%d)%d%d%d[v%d]*$");  year = tonumber(year);  month = tonumber(month);  if ((not (90 < year or 8 > year)) or (1 > month or 12 < month)) or -- if invalid year or invalid month  ((91 == year and 7 > month) or (7 == year and 3 < month)) then -- if years ok, are starting and ending months ok?  err_cat = true; -- flag for error message  end   elseif id:match("^%d%d[01]%d%.%d%d%d%d$") or id:match("^%d%d[01]%d%.%d%d%d%dv%d+$") then -- test for the 0704-1412 w/ & w/o version  year, month = id:match("^(%d%d)([01]%d)%.%d%d%d%d[v%d]*$");  year = tonumber(year);  month = tonumber(month);  if ((7 > year) or (14 < year) or (1 > month or 12 < month)) or -- is year invalid or is month invalid? (doesn't test for future years)  ((7 == year) and (4 > month)) then --or -- when year is 07, is month invalid (before April)?  err_cat = 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 w/ & w/o version  year, month = id:match("^(%d%d)([01]%d)%.%d%d%d%d%d[v%d]*$");  year = tonumber(year);  month = tonumber(month);  if ((15 > year) or (1 > month or 12 < month)) then -- is year invalid or is month invalid? (doesn't test for future years)  err_cat = true; -- flag for error message  end   else  err_cat = true; -- not a recognized format; flag for error message  end   err_cat = err_cat and table.concat ({' ', set_error ('bad_arxiv')}) or ''; -- set error message if flag is true   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}) .. err_cat;   if is_set (class) then  if id:match ('^%d+') then  text = table.concat ({text, ' [[//arxiv.org/archive/', class, ' ', class, ']]'}); -- external link within square brackets, not wikilink  else  text = table.concat ({text, ' ', set_error ('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: http://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 (id, access)  local handler = cfg.id_handlers['BIBCODE'];  local err_type;  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 its missing a letter)  end  end  end   if is_set (err_type) then -- if there was an error detected  text = text .. ' ' .. set_error( 'bad_bibcode', {err_type});  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(id)  local handler = cfg.id_handlers['BIORXIV'];  local err_cat = true; -- flag; assume that there will be an error   local patterns = {  '^10.1101/%d%d%d%d%d%d$', -- simple 6-digit identifier (before 2019-12-11)  '^10.1101/(20[1-9]%d)%.([01]%d)%.([0-3]%d)%.%d%d%d%d%d%dv%d+$', -- y.m.d. date + 6-digit identifier + version (after 2019-12-11)  '^10.1101/(20[1-9]%d)%.([01]%d)%.([0-3]%d)%.%d%d%d%d%d%d$', -- y.m.d. date + 6-digit identifier (after 2019-12-11)  }   for _, pattern in ipairs (patterns) do -- spin through the patterns looking for a match  if id:match (pattern) then  local y, m, d = id:match (pattern); -- found a match, attempt to get year, month and date from the identifier   if m then -- m is nil when id is the six-digit form  if not is_valid_biorxiv_date (y .. '-' .. m .. '-' .. d) then -- validate the encoded date; TODO: don't ignore leapyear and actual month lengths ({{#time:}} is a poor date validator)  break; -- date fail; break out early so we don't unset the error message  end  end  err_cat = nil; -- we found a match so unset the error message  break; -- and done  end  end -- err_cat remains set here when no match   return external_link_id ({link=handler.link, label=handler.label, q=handler.q, redirect=handler.redirect,  prefix=handler.prefix,id=id,separator=handler.separator,  encode=handler.encode, access=handler.access}) .. (err_cat and (' ' .. set_error( 'bad_biorxiv')) or ''); end   --[[--------------------------< C I T E S E E R X >------------------------------------------------------------  CiteSeerX use their own notion of "doi" (not to be confused with the identifiers resolved via doi.org).  The description of the structure of this identifier can be found at Help_talk:Citation_Style_1/Archive_26#CiteSeerX_id_structure ]]  local function citeseerx (id)  local handler = cfg.id_handlers['CITESEERX'];  local matched;   local text = external_link_id ({link=handler.link, label=handler.label, q=handler.q, redirect=handler.redirect,  prefix=handler.prefix, id=id, separator=handler.separator, encode=handler.encode,  access=handler.access});   matched = id:match ("^10%.1%.1%.[1-9]%d?%d?%d?%.[1-9]%d?%d?%d?$");  if not matched then  text = text .. ' ' .. set_error( 'bad_citeseerx' );  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.  ]]  local function doi(id, inactive, access)  local cat = ""  local handler = cfg.id_handlers['DOI'];   local text;  if is_set(inactive) then  local inactive_year = inactive:match("%d%d%d%d") or ''; -- try to get the year portion from the inactive date  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  else  inactive_year = nil; -- |doi-broken= has something but it isn't a date  end   if is_set(inactive_year) and is_set (inactive_month) then  table.insert( z.error_categories, 'Pages with DOIs inactive as of ' .. inactive_year .. ' ' .. inactive_month); -- use inactive month in category name  elseif is_set(inactive_year) then  table.insert( z.error_categories, 'Pages with DOIs inactive as of ' .. inactive_year);  else  table.insert( z.error_categories, 'Pages with inactive DOIs'); -- when inactive doesn't contain a recognizable date  end  inactive = " (" .. cfg.messages['inactive'] .. ' ' .. inactive .. ')';  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}) .. (inactive or '')   local registrant = id:match ('^10%.([^/]+)/[^%s–]-[^%.,]$'); -- registrant set when doi has the proper basic form   registrant_err_patterns = { -- these patterns are for code ranges that are not supported   '^[^1-3]%d%d%d%d%.%d%d*$', -- 5 digits with subcode (0xxxx, 40000+); accecpts: 10000–39999  '^[^1-4]%d%d%d%d$', -- 5 digits without subcode (0xxxx, 40000+); accecpts: 10000–49999  '^[^1-9]%d%d%d%.%d%d*$', -- 4 digits with subcode (0xxx); accecpts: 1000–9999  '^[^1-9]%d%d%d$', -- 4 digits without subcode (0xxx); accecpts: 1000–9999  '^%d%d%d%d%d%d+', -- 6 or more digits  '^%d%d?%d?$', -- less than 4 digits without subcode (with subcode is legitimate)  '^5555$', -- test registrant will never resolve  '%s', -- any space character in registrant  }   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  cat = ' ' .. set_error ('bad_doi'); -- when found, mark this doi as bad  break; -- and done  end  end  else  cat = ' ' .. set_error ('bad_doi'); -- invalid directory or malformed  end   return text .. cat 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: http://www.handle.net/proxy_servlet.html. query strings are not displayed but since '?' is anallowed 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(id, access)  local handler = cfg.id_handlers['HDL'];  local query_params = { -- list of known query parameters from http://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–]-[^%.,]$") then -- hdl must contain a fwd slash, must not contain spaces, endashes, and must not end with period or comma  text = text .. ' ' .. set_error( 'bad_hdl' );  end  return text; end   --[[--------------------------< I S B N >----------------------------------------------------------------------  Determines whether an ISBN string is valid  ]]  local function isbn( isbn_str )  if nil ~= isbn_str:match("[^%s-0-9X]") then  return false, cfg.err_msg_supl.char; -- fail if isbn_str contains anything but digits, hyphens, or the uppercase X  end  isbn_str = isbn_str:gsub( "-", "" ):gsub( " ", "" ); -- remove hyphens and spaces  local len = isbn_str:len();   if len ~= 10 and len ~= 13 then  return false, cfg.err_msg_supl.length; -- fail if incorrect length  end   if len == 10 then  if isbn_str:match( "^%d*X?$" ) == nil then -- fail if isbn_str has 'X' anywhere but last position  return false, cfg.err_msg_supl.form;  end  return is_valid_isxn(isbn_str, 10), cfg.err_msg_supl.check;  else  if isbn_str:match( "^%d+$" ) == nil then  return false, cfg.err_msg_supl.char; -- fail if isbn13 is not all digits  end  if isbn_str:match( "^97[89]%d*$" ) == nil then  return false, cfg.err_msg_supl.prefix; -- fail when isbn13 does not begin with 978 or 979  end  if isbn_str:match ('^9790') then  return false, cfg.err_msg_supl.group; -- group identifier '0' is reserved to ismn  end  return is_valid_isxn_13 (isbn_str), cfg.err_msg_supl.check;  end end   --[[--------------------------< A M A Z O N >------------------------------------------------------------------  Formats a link to Amazon. Do simple error checking: asin must be mix of 10 numeric or uppercase alpha characters. If a mix, first character must be uppercase alpha; if all numeric, asins must be 10-digit isbn. If 10-digit isbn, add a maintenance category so a bot or awb script can replace |asin= with |isbn=. Error message if not 10 characters, if not isbn10, if mixed and first character is a digit.  This function is positioned here because it calls isbn()  ]]  local function asin(id, domain)  local err_cat = ""   if not id:match("^[%d%u][%d%u][%d%u][%d%u][%d%u][%d%u][%d%u][%d%u][%d%u][%d%u]$") then  err_cat = ' ' .. set_error ('bad_asin'); -- asin is not a mix of 10 uppercase alpha and numeric characters  else  if id:match("^%d%d%d%d%d%d%d%d%d[%dX]$") then -- if 10-digit numeric (or 9 digits with terminal X)  if isbn( id ) then -- see if asin value is isbn10  add_maint_cat ('ASIN');  elseif not is_set (err_cat) then  err_cat = ' ' .. set_error ('bad_asin'); -- asin is not isbn10  end  elseif not id:match("^%u[%d%u]+$") then  err_cat = ' ' .. set_error ('bad_asin'); -- asin doesn't begin with uppercase alpha  end  end  if not is_set(domain) then  domain = "com";  elseif in_array (domain, {'jp', 'uk'}) then -- Japan, United Kingdom  domain = "co." .. domain;  elseif in_array (domain, {'au', 'br', 'mx'}) then -- Australia, Brazil, Mexico  domain = "com." .. domain;  end  local handler = cfg.id_handlers['ASIN'];  return external_link_id ({link=handler.link, label=handler.label, q=handler.q, redirect=handler.redirect,  prefix=handler.prefix .. domain .. "/dp/",  id=id, encode=handler.encode, separator = handler.separator}) .. err_cat; end   --[[--------------------------< I S M N >----------------------------------------------------------------------  Determines whether an ISMN string is valid. Similar to isbn-13, ismn is 13 digits begining 979-0-... and uses the same check digit calculations. See http://www.ismn-international.org/download/Web_ISMN_Users_Manual_2008-6.pdf section 2, pages 9–12.  ]]  local function ismn (id)  local handler = cfg.id_handlers['ISMN'];  local text;  local valid_ismn = true;  local id_copy;   id_copy = id; -- save a copy because this testing is destructive  id=id:gsub( "[%s-–]", "" ); -- strip spaces, hyphens, and endashes from the ismn   if 13 ~= id:len() or id:match( "^9790%d*$" ) == nil then -- ismn must be 13 digits and begin 9790  valid_ismn = false;  else  valid_ismn=is_valid_isxn_13 (id); -- validate ismn  end  -- text = internal_link_id ({link=handler.link, label=handler.label, 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})   local label_link = (cfg.use_identifier_redirects and is_set (handler.redirect) and handler.redirect) or wd_article or handler.link; -- because no place to link to yet   text = table.concat ( -- because no place to link to yet  {  make_wikilink (label_link, handler.label),  handler.separator,  id_copy  });   if false == valid_ismn then  text = text .. ' ' .. set_error( 'bad_ismn' ) -- add 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: [http://www.worldcat.org/issn/0819 4327 0819 4327] -- can't have spaces in an external link   This code now prevents that by inserting a hyphen at the issn midpoint. It also validates the issn for length and makes sure that the checkdigit agrees with the calculated value. Incorrect length (8 digits), characters other than 0-9 and X, or checkdigit / calculated value mismatch will all cause a check issn error message. The issn is always displayed with a hyphen, even if the issn was given as a single group of 8 digits.  ]]  local function issn(id, e)  local issn_copy = id; -- save a copy of unadulterated issn; use this version for display if issn does not validate  local handler;  local text;  local valid_issn = true;   if e then  handler = cfg.id_handlers['EISSN'];  else  handler = cfg.id_handlers['ISSN'];  end   id=id:gsub( "[%s-–]", "" ); -- strip spaces, hyphens, and endashes from the issn   if 8 ~= id:len() or nil == id:match( "^%d*X?$" ) then -- validate the issn: 8 digits long, containing only 0-9 or X in the last position  valid_issn=false; -- wrong length or improper character  else  valid_issn=is_valid_isxn(id, 8); -- validate issn  end   if true == valid_issn then  id = string.sub( id, 1, 4 ) .. "-" .. string.sub( id, 5 ); -- if valid, display correctly formatted version  else  id = issn_copy; -- if not valid, use the show the invalid issn with error message  end   text = external_link_id ({link=handler.link, label=handler.label, q=handler.q, redirect=handler.redirect,  prefix=handler.prefix,id=id,separator=handler.separator, encode=handler.encode})   if false == valid_issn then  text = text .. ' ' .. set_error( 'bad_issn', e and 'e' or '' ) -- add an error message if the issn is invalid  end   return text end   --[[--------------------------< J F M >-----------------------------------------------------------------------  A numerical identifier in the form nn.nnnn.nn  ]]  local function jfm (id)  local handler = cfg.id_handlers['JFM'];  local id_num;  local err_cat = '';   id_num = id:match ('^[Jj][Ff][Mm](.*)$'); -- identifier with jfm prefix; extract identifier   if is_set (id_num) then  add_maint_cat ('jfm_format');  else -- plain number without mr 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  err_cat = ' ' .. set_error( 'bad_jfm' ); -- set an 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}) .. err_cat; 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. http://info-uri.info/registry/OAIHandler?verb=GetRecord&metadataPrefix=reg&identifier=info:lccn/  length = 8 then all digits length = 9 then lccn[1] is lower case alpha length = 10 then lccn[1] and lccn[2] are both lower case alpha or both digits length = 11 then lccn[1] is lower case alpha, lccn[2] and lccn[3] are both lower case alpha or both digits length = 12 then lccn[1] and lccn[2] are both lower case alpha  ]]  local function lccn(lccn)  local handler = cfg.id_handlers['LCCN'];  local err_cat = ''; -- presume that LCCN is valid  local id = lccn; -- local copy of the lccn   id = normalize_lccn (id); -- get canonical form (no whitespace, hyphens, forward slashes)  local len = id:len(); -- get the length of the lccn   if 8 == len then  if id:match("[^%d]") then -- if LCCN has anything but digits (nil if only digits)  err_cat = ' ' .. set_error( 'bad_lccn' ); -- set an error message  end  elseif 9 == len then -- LCCN should be adddddddd  if nil == id:match("%l%d%d%d%d%d%d%d%d") then -- does it match our pattern?  err_cat = ' ' .. set_error( 'bad_lccn' ); -- set an error message  end  elseif 10 == len then -- LCCN should be aadddddddd or dddddddddd  if id:match("[^%d]") then -- if LCCN has anything but digits (nil if only digits) ...  if nil == id:match("^%l%l%d%d%d%d%d%d%d%d") then -- ... see if it matches our pattern  err_cat = ' ' .. set_error( 'bad_lccn' ); -- no match, set an error message  end  end  elseif 11 == len then -- LCCN should be aaadddddddd or adddddddddd  if not (id:match("^%l%l%l%d%d%d%d%d%d%d%d") or id:match("^%l%d%d%d%d%d%d%d%d%d%d")) then -- see if it matches one of our patterns  err_cat = ' ' .. set_error( 'bad_lccn' ); -- no match, set an error message  end  elseif 12 == len then -- LCCN should be aadddddddddd  if not id:match("^%l%l%d%d%d%d%d%d%d%d%d%d") then -- see if it matches our pattern  err_cat = ' ' .. set_error( 'bad_lccn' ); -- no match, set an error message  end  else  err_cat = ' ' .. set_error( 'bad_lccn' ); -- wrong length, set an error message  end   if not is_set (err_cat) and nil ~= lccn:find ('%s') then  err_cat = ' ' .. set_error( 'bad_lccn' ); -- lccn contains a space, set an error message  end   return external_link_id ({link=handler.link, label=handler.label, q=handler.q, redirect=handler.redirect,  prefix=handler.prefix,id=lccn,separator=handler.separator, encode=handler.encode}) .. err_cat; end   --[[--------------------------< M R >--------------------------------------------------------------------------  A seven digit number; if not seven digits, zero-fill leading digits to make seven digits.  ]]  local function mr (id)  local handler = cfg.id_handlers['MR'];  local id_num;  local id_len;  local err_cat = '';   id_num = id:match ('^[Mm][Rr](%d+)$'); -- identifier with mr prefix   if is_set (id_num) then  add_maint_cat ('mr_format');  else -- plain number without mr prefix  id_num = id:match ('^%d+$'); -- if here id is all digits  end   id_len = id_num and id_num:len() or 0;  if (7 >= id_len) and (0 ~= id_len) then  id = string.rep ('0', 7-id_len ) .. id_num; -- zero-fill leading digits  else  err_cat = ' ' .. set_error( 'bad_mr' ); -- set an error message  end   return external_link_id ({link=handler.link, label=handler.label, q=handler.q, redirect=handler.redirect,  prefix=handler.prefix,id=id,separator=handler.separator, encode=handler.encode}) .. err_cat; end   --[[--------------------------< O C L C >----------------------------------------------------------------------  Validate and format an oclc id. https://www.oclc.org/batchload/controlnumber.en.html {{dead link}} archived at: https://web.archive.org/web/20161228233804/https://www.oclc.org/batchload/controlnumber.en.html  ]]  local function oclc (id)  local handler = cfg.id_handlers['OCLC'];  local number;  local err_msg = ''; -- empty string for concatenation   if id:match('^ocm%d%d%d%d%d%d%d%d$') 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; -- contrain to 1 to 9 digits; change this when oclc issues 10-digit numbers  end  elseif id:match('^%d+$') then -- no prefix  number = id; -- get the number  if 10 < number:len() then  number = nil; -- contrain to 1 to 10 digits; change this when oclc issues 11-digit numbers  end  end   if number then -- proper format  id = number; -- exclude prefix, if any, from external link  else  err_msg = ' ' .. set_error( 'bad_oclc' ) -- add an error message if the id is malformed  end   local text = external_link_id ({link=handler.link, label=handler.label, q=handler.q, redirect=handler.redirect,  prefix=handler.prefix, id=id, separator=handler.separator, encode=handler.encode}) .. err_msg;   return text; end   --[[--------------------------< O P E N L I B R A R Y >--------------------------------------------------------  Formats an OpenLibrary link, and checks for associated errors.  ]]  local function openlibrary(id, access)  local code;  local handler = cfg.id_handlers['OL'];  local ident;   ident, code = id:gsub('^OL', ''):match("^(%d+([AMW]))$"); -- optional OL prefix followed immediately by digits followed by 'A', 'M', or 'W'; remove OL prefix   if not is_set (ident) then -- if malformed return an error  return external_link_id ({link=handler.link, label=handler.label, q=handler.q, redirect=handler.redirect,  prefix=handler.prefix .. 'OL',  id=id, separator=handler.separator, encode = handler.encode,  access = access}) .. ' ' .. set_error( 'bad_ol' );  end   id = ident; -- use ident without the optional OL prefix (it has been removed)   if ( code == "A" ) then  return external_link_id ({link=handler.link, label=handler.label, q=handler.q, redirect=handler.redirect,  prefix=handler.prefix .. 'authors/OL',  id=id, separator=handler.separator, encode = handler.encode,  access = access})  end   if ( code == "M" ) then  return external_link_id ({link=handler.link, label=handler.label, q=handler.q, redirect=handler.redirect,  prefix=handler.prefix .. 'books/OL',  id=id, separator=handler.separator, encode = handler.encode,  access = access})  end   if ( code == "W" ) then  return external_link_id ({link=handler.link, label=handler.label, q=handler.q, redirect=handler.redirect,  prefix=handler.prefix .. 'works/OL',  id=id, separator=handler.separator, encode = handler.encode,  access = access})  end end   --[[--------------------------< P M C >------------------------------------------------------------------------  Format a PMC, do simple error checking, and check for embargoed articles.  The embargo parameter takes a date for a value. If the embargo date is in the future the PMC identifier will not be linked to the article. If the embargo date is today or in the past, or if it is empty or omitted, then the PMC identifier is linked to the article through the link at cfg.id_handlers['PMC'].prefix.  PMC embargo date testing is done in function is_embargoed () which is called earlier because when the citation has |pmc=<value> but does not have a |url= then |title= is linked with the PMC link. Function is_embargoed () returns the embargo date if the PMC article is still embargoed, otherwise it returns an empty string.  PMCs are sequential numbers beginning at 1 and counting up. This code checks the PMC to see that it contains only digits and is less than test_limit; the value in local variable test_limit will need to be updated periodically as more PMCs are issued.  ]]  local function pmc(id, embargo)  local handler = cfg.id_handlers['PMC'];  local err_cat = ''; -- presume that PMC is valid  local id_num;  local text;   id_num = id:match ('^[Pp][Mm][Cc](%d+)$'); -- identifier with pmc prefix   if is_set (id_num) then  add_maint_cat ('pmc_format');  else -- plain number without pmc prefix  id_num = id:match ('^%d+$'); -- 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_cat = ' ' .. set_error( 'bad_pmc' ); -- set an error message  else  id = tostring (id_num); -- make sure id is a string  end  else -- when id format incorrect  err_cat = ' ' .. set_error( 'bad_pmc' ); -- set an error message  end   if is_set (embargo) then -- is PMC is still embargoed?  text = table.concat ( -- still embargoed so no external link  {  make_wikilink (handler.link, handler.label),  handler.separator,  id,  err_cat  });  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}) .. err_cat;  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(id)  local handler = cfg.id_handlers['PMID'];  local err_cat = ''; -- presume that PMID is valid   if id:match("[^%d]") then -- if PMID has anything but digits  err_cat = ' ' .. set_error( 'bad_pmid' ); -- set an error message  else -- PMID is only digits  local id_num = tonumber(id); -- convert id to a number for range testing  if 1 > id_num or handler.id_limit < id_num then -- if PMID is outside test limit boundaries  err_cat = ' ' .. set_error( 'bad_pmid' ); -- set an error message  end  end   return external_link_id ({link=handler.link, label=handler.label, q=handler.q, redirect=handler.redirect,  prefix=handler.prefix,id=id,separator=handler.separator, encode=handler.encode}) .. err_cat; 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 (id, access)  local handler = cfg.id_handlers['S2CID'];  local err_cat = ''; -- presume that S2CID is valid  local id_num;  local text;   id_num = id:match ('^[1-9]%d*$'); -- id must be all digits; must not begin with 0; no open access flag   if is_set (id_num) then -- id_num has a value so test it  id_num = tonumber(id_num); -- convert id_num to a number for range testing  if handler.id_limit < id_num then -- if S2CID is outside test limit boundaries  err_cat = ' ' .. set_error( 'bad_s2cid' ); -- set an error message  end   else -- when id format incorrect  err_cat = ' ' .. set_error( 'bad_s2cid' ); -- set an error message  end   text = external_link_id ({link=handler.link, label=handler.label, q=handler.q, redirect=handler.redirect,  prefix=handler.prefix, id=id:gsub ('%.%a%a', ''), separator=handler.separator, encode=handler.encode, access=access}) .. err_cat;   return text; end   --[[--------------------------< S B N >------------------------------------------------------------------------  9-digit form of isbn10; uses same check-digit validation when sbn is prefixed with an additional '0' to make 10 digits  ]]  local function sbn (id)  local check;  local err_type = '';   if nil ~= id:match("[^%s-0-9X]") then  return false, cfg.err_msg_supl.char; -- fail if sbn contains anything but digits, hyphens, or the uppercase X  end   id=id:gsub( "[%s-]", "" ); -- strip spaces and hyphens from the sbn   if 9 ~= id:len() then  return false, cfg.err_msg_supl.length; -- fail if incorrect length  end   if id:match( "^%d*X?$" ) == nil then -- fail if sbn has 'X' anywhere but last position  return false, cfg.err_msg_supl.form;  end   return is_valid_isxn('0' .. id, 10), cfg.err_msg_supl.check; -- prefix sbn with '0' and validate as isbn10 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 (id)  local handler = cfg.id_handlers['SSRN'];  local err_cat = ''; -- presume that SSRN is valid  local id_num;  local text;   id_num = id:match ('^%d+$'); -- id must be all digits   if is_set (id_num) then -- id_num has a value so test it  id_num = tonumber(id_num); -- convert id_num to a number for range testing  if 100 > id_num or handler.id_limit < id_num then -- if SSRN is outside test limit boundaries  err_cat = ' ' .. set_error( 'bad_ssrn' ); -- set an error message  end  else -- when id format incorrect  err_cat = ' ' .. set_error( 'bad_ssrn' ); -- set an error message  end   text = external_link_id ({link=handler.link, label=handler.label, q=handler.q, redirect=handler.redirect,  prefix=handler.prefix,id=id,separator=handler.separator, encode=handler.encode, access=handler.access}) .. err_cat;   return text; end   --[[--------------------------< U S E N E T _ I D >------------------------------------------------------------  Validate and format a usenet message id. Simple error checking, looks for 'id-left@id-right' not enclosed in '<' and/or '>' angle brackets.  ]]  local function usenet_id (id)  local handler = cfg.id_handlers['USENETID'];   local text = external_link_id ({link=handler.link, label=handler.label, q=handler.q, redirect=handler.redirect,  prefix=handler.prefix,id=id,separator=handler.separator, encode=handler.encode})   if not id:match('^.+@.+$') or not id:match('^[^<].*[^>]$')then -- doesn't have '@' or has one or first or last character is '< or '>'  text = text .. ' ' .. set_error( 'bad_usenet_id' ) -- add an error message if the message id is invalid  end   return text end   --[[--------------------------< Z B L >-----------------------------------------------------------------------  A numerical identifier in the form nnnn.nnnnn - leading zeros in the first quartet optional  format described here: http://emis.mi.sanu.ac.rs/ZMATH/zmath/en/help/search/  temporary format is apparently eight digits. Anything else is an error  ]]  local function zbl (id)  local handler = cfg.id_handlers['ZBL'];  local err_cat = '';   if id:match('^%d%d%d%d%d%d%d%d$') then -- is this identifier using temporary format?  add_maint_cat ('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?  err_cat = ' ' .. set_error( 'bad_zbl' ); -- no, set an 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}) .. err_cat; end   --============================<< I N T E R F A C E F U N C T I O N S >>==========================================  --[[--------------------------< B U I L D _ I D _ L I S T >--------------------------------------------------------  Takes a table of IDs created by extract_ids() and turns it into a table of formatted ID outputs.  inputs:  id_list – table of identifiers built by extract_ids()  options – table of various template parameter values used to modify some manually handled identifiers  ]]  local function build_id_list( id_list, options )  local new_list, handler = {};   local function fallback(k) return { __index = function(t,i) return cfg.id_handlers[k][i] end } end;   for k, v in pairs( id_list ) do -- k is uc identifier name as index to cfg.id_handlers; e.g. cfg.id_handlers['ISBN'], v is a table  -- fallback to read-only cfg  handler = setmetatable( { ['id'] = v, ['access'] = options.IdAccessLevels[k] }, fallback(k) );   if handler.mode == 'external' then  table.insert( new_list, {handler.label, external_link_id( handler ) } );  elseif handler.mode == 'internal' then  table.insert( new_list, {handler.label, internal_link_id( handler ) } );  elseif handler.mode ~= 'manual' then  error( cfg.messages['unknown_ID_mode'] );  elseif k == 'ARXIV' then  table.insert( new_list, {handler.label, arxiv( v, options.Class ) } );  elseif k == 'ASIN' then  table.insert( new_list, {handler.label, asin( v, options.ASINTLD ) } );  elseif k == 'BIBCODE' then  table.insert( new_list, {handler.label, bibcode( v, handler.access ) } );  elseif k == 'BIORXIV' then  table.insert( new_list, {handler.label, biorxiv( v ) } );  elseif k == 'CITESEERX' then  table.insert( new_list, {handler.label, citeseerx( v ) } );  elseif k == 'DOI' then  table.insert( new_list, {handler.label, doi( v, options.DoiBroken, handler.access ) } );  elseif k == 'EISSN' then  table.insert( new_list, {handler.label, issn( v, true ) } ); -- true distinguishes eissn from issn  elseif k == 'HDL' then  table.insert( new_list, {handler.label, hdl( v, handler.access ) } );  elseif k == 'ISBN' then  local ISBN = internal_link_id( handler );  local check;  local err_type = '';  check, err_type = isbn( v );  if not check then  if is_set(options.IgnoreISBN) then -- ISBN is invalid; if |ignore-isbn-error= set  add_maint_cat ('ignore_isbn_err'); -- ad a maint category  else  ISBN = ISBN .. set_error( 'bad_isbn', {err_type}, false, " ", "" ); -- else display an error message  end  elseif is_set(options.IgnoreISBN) then -- ISBN is OK; if |ignore-isbn-error= set  add_maint_cat ('ignore_isbn_err'); -- because |ignore-isbn-error= unnecessary  end  table.insert( new_list, {handler.label, ISBN } );  elseif k == 'ISMN' then  table.insert( new_list, {handler.label, ismn( v ) } );  elseif k == 'ISSN' then  table.insert( new_list, {handler.label, issn( v ) } );  elseif k == 'JFM' then  table.insert( new_list, {handler.label, jfm( v ) } );  elseif k == 'LCCN' then  table.insert( new_list, {handler.label, lccn( v ) } );  elseif k == 'MR' then  table.insert( new_list, {handler.label, mr( v ) } );  elseif k == 'OCLC' then  table.insert( new_list, {handler.label, oclc( v ) } );  elseif k == 'OL' or k == 'OLA' then  table.insert( new_list, {handler.label, openlibrary( v, handler.access ) } );  elseif k == 'PMC' then  table.insert( new_list, {handler.label, pmc( v, options.Embargo ) } );  elseif k == 'PMID' then  table.insert( new_list, {handler.label, pmid( v ) } );  elseif k == 'S2CID' then  table.insert( new_list, {handler.label, s2cid( v, handler.access ) } );  elseif k == 'SBN' then  local SBN = internal_link_id (handler);  local check; -- boolean validation result  local err_type = '';  check, err_type = sbn (v);  if not check then  SBN = SBN .. set_error( 'bad_sbn', {err_type}, false, " ", "" ); -- display an error message  end  table.insert( new_list, {handler.label, SBN } );  elseif k == 'SSRN' then  table.insert( new_list, {handler.label, ssrn( v ) } );  elseif k == 'USENETID' then  table.insert( new_list, {handler.label, usenet_id( v ) } );  elseif k == 'ZBL' then  table.insert( new_list, {handler.label, zbl( v ) } );  else  error( cfg.messages['unknown_manual_ID'] );  end  end   local function comp( a, b ) -- used in following table.sort()  return a[1]:lower() < b[1]:lower();  end   table.sort( new_list, comp );  for k, v in ipairs( new_list ) do  new_list[k] = v[2];  end   return new_list; end   --[[--------------------------< 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 is more than one alias exists in args  ]]  local function extract_ids( args )  local id_list = {}; -- list of identifiers found in args  for k, v in pairs( cfg.id_handlers ) do -- k is uc identifier name as index to cfg.id_handlers; e.g. cfg.id_handlers['ISBN'], v is a table  v = select_one( args, v.parameters, 'redundant_parameters' ); -- v.parameters is a table of aliases for k; here we pick one from args if present  if is_set(v) then id_list[k] = v; end -- if found in args, add identifier to our list  end  return id_list; end   --[[--------------------------< 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.  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  table.insert( z.message_tail, { set_error( 'invalid_param_val', {access_param, access_level}, true ) } );  access_level = nil; -- invalid so unset  end  if not is_set(id_list[k]) then -- identifer access-level must have a matching identifier  table.insert( z.message_tail, { set_error( 'param_access_requires_param', {k:lower()}, true ) } ); -- param 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   --[[--------------------------< 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;   is_set = utilities_page_ptr.is_set; -- import functions from select Module:Citation/CS1/Utilities module  in_array = utilities_page_ptr.in_array;  set_error = utilities_page_ptr.set_error;  select_one = utilities_page_ptr.select_one;  add_maint_cat = utilities_page_ptr.add_maint_cat;  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 {  build_id_list = build_id_list,  extract_ids = extract_ids,  extract_id_access_levels = extract_id_access_levels,  is_embargoed = is_embargoed;  set_selected_modules = set_selected_modules;  }