loop through a list of parameters and their values. Look at the value and if it has an external link, emit an error message.  
local function check_for_url (parameter_list, error_list)
for k, v in pairs (parameter_list) do -- for each parameter in the list
if is_parameter_ext_wikilink (v) then -- look at the value; if there is a URL add an error message
table.insert (error_list, utilities.wrap_style ('parameter', k));
end
end
end  
----------------------------< S A F E _ F O R _ U R L >------------------------------------------------------  
Escape sequences for content that will be used for URL descriptions  
local function safe_for_url( str )
if str:match( "%[%[.-%]%]" ) ~= nil then
utilities.set_message ('err_wikilink_in_url', {});
end  
return str:gsub( '[%[%]\n]', {
['['] = '&#91;',
[']'] = '&#93;',
['\n'] = ' ' } );
end  
----------------------------< E X T E R N A L _ L I N K >----------------------------------------------------  
Format an external link with error checking  
local function external_link (URL, label, source, access)
local err_msg = '';
local domain;
local path;
local base_url;  
if not utilities.is_set (label) then
label = URL;
if utilities.is_set (source) then
utilities.set_message ('err_bare_url_missing_title', {utilities.wrap_style ('parameter', source)});
else
error (cfg.messages["bare_url_no_origin"]); -- programmer error; valid parameter name does not have matching meta-parameter
end
end
if not check_url (URL) then
utilities.set_message ('err_bad_url', {utilities.wrap_style ('parameter', source)});
end  
domain, path = URL:match ('^([/%.%-%+:%a%d]+)([/%?#].*)$'); -- split the URL into scheme plus domain and path
if path then -- if there is a path portion
path = path:gsub ('[%[%]]', {['['] = '%5b', [']'] = '%5d'}); -- replace '[' and ']' with their percent-encoded values
URL = table.concat ({domain, path}); -- and reassemble
end  
base_url = table.concat ({ "[", URL, " ", safe_for_url (label), "]" }); -- assemble a wiki-markup URL  
if utilities.is_set (access) then -- access level (subscription, registration, limited)
base_url = utilities.substitute (cfg.presentation['ext-link-access-signal'], {cfg.presentation[access].class, cfg.presentation[access].title, base_url}); -- add the appropriate icon
end  
return base_url;
end  
----------------------------< D E P R E C A T E D _ P A R A M E T E R >--------------------------------------  
Categorize and emit an error message when the citation contains one or more deprecated parameters. The function includes the
offending parameter name to the error message. Only one error message is emitted regardless of the number of deprecated
parameters in the citation.  
added_deprecated_cat is a Boolean declared in page scope variables above  
local function deprecated_parameter(name)
if not added_deprecated_cat then
added_deprecated_cat = true; -- note that we've added this category
utilities.set_message ('err_deprecated_params', {name}); -- add error message
end
end  
--[=[-------------------------< K E R N _ Q U O T E S >--------------------------------------------------------  
Apply kerning to open the space between the quote mark provided by the module and a leading or trailing quote
mark contained in a |title= or |chapter= parameter's value.  
This function will positive kern either single or double quotes:
"'Unkerned title with leading and trailing single quote marks'"
" 'Kerned title with leading and trailing single quote marks' " (in real life the kerning isn't as wide as this example)
Double single quotes (italic or bold wiki-markup) are not kerned.  
Replaces Unicode quote marks in plain text or in the label portion of a D style wikilink with typewriter
quote marks regardless of the need for kerning. Unicode quote marks are not replaced in simple D wikilinks.  
Call this function for chapter titles, for website titles, etc.; not for book titles.  
]=]  
local function kern_quotes (str)
local cap = '';
local wl_type, label, link;  
wl_type, label, link = utilities.is_wikilink (str); -- wl_type is: 0, no wl (text in label variable); 1, D; 2, D  
if 1 == wl_type then -- D simple wikilink with or without quote marks
if mw.ustring.match (str, '%[%[[\"“”\'‘’].+[\"“”\'‘’]%]%]') then -- leading and trailing quote marks
str = utilities.substitute (cfg.presentation['kern-'], str);
str = utilities.substitute (cfg.presentation['kern-'], str);
elseif mw.ustring.match (str, '%[%[[\"“”\'‘’].+%]%]') then -- leading quote marks
str = utilities.substitute (cfg.presentation['kern-'], str);
elseif mw.ustring.match (str, '%[%[.+[\"“”\'‘’]%]%]') then -- trailing quote marks
str = utilities.substitute (cfg.presentation['kern-'], str);
end  
else -- plain text or D; text in label variable
label = mw.ustring.gsub (label, '[“”]', '\"'); -- replace “” (U+201C & U+201D) with " (typewriter double quote mark)
label = mw.ustring.gsub (label, '[‘’]', '\''); -- replace ‘’ (U+2018 & U+2019) with ' (typewriter single quote mark)  
cap = mw.ustring.match (label, "^([\"\'][^\'].+)"); -- match leading double or single quote but not doubled single quotes (italic markup)
if utilities.is_set (cap) then
label = utilities.substitute (cfg.presentation['kern-'], cap);
end  
cap = mw.ustring.match (label, "^(.+[^\'][\"\'])$") -- match trailing double or single quote but not doubled single quotes (italic markup)
if utilities.is_set (cap) then
label = utilities.substitute (cfg.presentation['kern-'], cap);
end  
if 2 == wl_type then
str = utilities.make_wikilink (link, label); -- reassemble the wikilink
else
str = label;
end
end
return str;
end  
--script-title= holds title parameters that are not written in Latin-based scripts: Chinese, Japanese, Arabic, Hebrew, etc. These scripts should
not be italicized and may be written -to-. The value supplied by |script-title= is concatenated onto Title after Title has been wrapped
in italic markup.  
Regardless of language, all values provided by |script-title= are wrapped in <bdi>...</bdi> tags to isolate RTL languages from the English to .  
|script-title= provides a unique feature. The value in |script-title= may be prefixed with a two-character ISO 639-1 language code and a colon:
|script-title=ja:*** *** (where * represents a Japanese character)
Spaces between the two-character code and the colon and the colon and the first script character are allowed:
|script-title=ja : *** ***
|script-title=ja: *** ***
|script-title=ja :*** ***
Spaces preceding the prefix are allowed: |script-title = ja:*** ***  
The prefix is checked for validity. If it is a valid ISO 639-1 language code, the lang attribute (lang="ja") is added to the <bdi> tag so that browsers can
know the language the tag contains. This may help the browser render the script more correctly. If the prefix is invalid, the lang attribute
is not added. At this time there is no error message for this condition.  
Supports |script-title=, |script-chapter=, |script-<periodical>=  
local function format_script_value (script_value, script_param)
local lang=''; -- initialize to empty string
local name;
if script_value:match('^%l%l%l?%s*:') then -- if first 3 or 4 non-space characters are script language prefix
lang = script_value:match('^(%l%l%l?)%s*:%s*%S.*'); -- get the language prefix or nil if there is no script
if not utilities.is_set (lang) then
utilities.set_message ('err_script_parameter', {script_param, cfg.err_msg_supl['missing title part']}); -- prefix without 'title'; add error message
return ''; -- script_value was just the prefix so return empty string
end
-- if we get this far we have prefix and script
name = cfg.lang_tag_remap[lang] or mw.language.fetchLanguageName( lang, cfg.this_wiki_code ); -- get language name so that we can use it to categorize
if utilities.is_set (name) then -- is prefix a proper ISO 639-1 language code?
script_value = script_value:gsub ('^%l+%s*:%s*', ''); -- strip prefix from script
-- is prefix one of these language codes?
if utilities.in_array (lang, cfg.script_lang_codes) then