local etal = false; -- return value set to true when we find some form of et al. vauthors parameter
local last, first, link, mask, suffix;
local corporate = false;  
vparam, etal = name_has_etal (vparam, etal, true); -- find and remove variations on et al. do not categorize (do it here because et al. might have a period)
v_name_table = get_v_name_table (vparam, v_name_table, v_link_table); -- names are separated by commas  
for i, v_name in ipairs(v_name_table) do
first = ''; -- set to empty string for concatenation and because it may have been set for previous author/editor
local accept_name;
v_name, accept_name = utilities.has_accept_as_written (v_name); -- remove accept-this-as-written markup when it wraps all of <v_name>  
if accept_name then
last = v_name;
corporate = true; -- flag used in list_people
elseif string.find(v_name, "%s") then
if v_name:find('[;%.]') then -- look for commonly occurring punctuation characters;
add_vanc_error (cfg.err_msg_supl.punctuation, i);
end
local lastfirstTable = {}
lastfirstTable = mw.text.split(v_name, "%s+")
first = table.remove(lastfirstTable); -- removes and returns value of last element in table which should be initials or generational suffix  
if not mw.ustring.match (first, '^%u+$') then -- mw.ustring here so that later we will catch non-Latin characters
suffix = first; -- not initials so assume that whatever we got is a generational suffix
first = table.remove(lastfirstTable); -- get what should be the initials from the table
end
last = table.concat(lastfirstTable, ' ') -- returns a string that is the concatenation of all other names that are not initials and generational suffix
if not utilities.is_set (last) then
first = ''; -- unset
last = v_name; -- last empty because something wrong with first
add_vanc_error (cfg.err_msg_supl.name, i);
end
if mw.ustring.match (last, '%a+%s+%u+%s+%a+') then
add_vanc_error (cfg.err_msg_supl['missing comma'], i); -- matches last II last; the case when a comma is missing
end
if mw.ustring.match (v_name, ' %u %u$') then -- this test is in the wrong place TODO: move or replace with a more appropriate test
add_vanc_error (cfg.err_msg_supl.initials, i); -- matches a space between two initials
end
else
last = v_name; -- last name or single corporate name? Doesn't support multiword corporate names? do we need this?
end  
if utilities.is_set (first) then
if not mw.ustring.match (first, "^%u?%u$") then -- first shall contain one or two upper-case letters, nothing else
add_vanc_error (cfg.err_msg_supl.initials, i); -- too many initials; mixed case initials (which may be ok Romanization); hyphenated initials
end
is_good_vanc_name (last, first, suffix, i); -- check first and last before restoring the suffix which may have a non-Latin digit
if utilities.is_set (suffix) then
first = first .. ' ' .. suffix; -- if there was a suffix concatenate with the initials
suffix = ''; -- unset so we don't add this suffix to all subsequent names
end
else
if not corporate then
is_good_vanc_name (last, '', nil, i);
end
end  
link = utilities.select_one ( args, cfg.aliases[list_name .. '-Link'], 'err_redundant_parameters', i ) or v_link_table[i];
mask = utilities.select_one ( args, cfg.aliases[list_name .. '-Mask'], 'err_redundant_parameters', i );
names[i] = {last = last, first = first, link = link, mask = mask, corporate = corporate}; -- add this assembled name to our names list
end
return names, etal; -- all done, return our list of names
end  
--authors=, |authorn= / |lastn / firstn=, or |vauthors= as the source of the author name list or
select one of |editorn= / editor-lastn= / |editor-firstn= or |veditors= as the source of the editor name list.  
Only one of these appropriate three will be used. The hierarchy is: |authorn= (and aliases) highest and |authors= lowest;
|editorn= (and aliases) highest and |veditors= lowest (support for |editors= withdrawn)  
When looking for |authorn= / |editorn= parameters, test |xxxxor1= and |xxxxor2= (and all of their aliases); stops after the second
test which mimicks the test used in extract_names when looking for a hole in the author name list. There may be a better
way to do this, I just haven't discovered what that way is.  
Emits an error message when more than one xxxxor name source is provided.  
In this function, vxxxxors = vauthors or veditors; xxxxors = authors as appropriate.  
local function select_author_editor_source (vxxxxors, xxxxors, args, list_name)
local lastfirst = false;
if utilities.select_one ( args, cfg.aliases[list_name .. '-Last'], '', 1 ) or -- do this twice in case we have a |first1= without a |last1=; this ...
utilities.select_one ( args, cfg.aliases[list_name .. '-First'], '', 1 ) or -- ... also catches the case where |first= is used with |vauthors=
utilities.select_one ( args, cfg.aliases[list_name .. '-Last'], '', 2 ) or
utilities.select_one ( args, cfg.aliases[list_name .. '-First'], '', 2 ) then
lastfirst = true;
end  
if (utilities.is_set (vxxxxors) and true == lastfirst) or -- these are the three error conditions
(utilities.is_set (vxxxxors) and utilities.is_set (xxxxors)) or
(true == lastfirst and utilities.is_set (xxxxors)) then
local err_name;
if 'AuthorList' == list_name then -- figure out which name should be used in error message
err_name = 'author';
else
err_name = 'editor';
end
utilities.set_message ('err_redundant_parameters', err_name .. '-name-list parameters'); -- add error message
end  
if true == lastfirst then return 1 end; -- return a number indicating which author name source to use
if utilities.is_set (vxxxxors) then return 2 end;
if utilities.is_set (xxxxors) then return 3 end;
return 1; -- no authors so return 1; this allows missing author name test to run in case there is a first without last
end  
----------------------------< I S _ V A L I D _ P A R A M E T E R _ V A L U E >------------------------------  
This function is used to validate a parameter's assigned value for those parameters that have only a limited number
of allowable values (yes, y, true, live, dead, etc.). When the parameter value has not been assigned a value (missing
or empty in the source template) the function returns the value specified by ret_val. If the parameter value is one
of the list of allowed values returns the translated value; else, emits an error message and returns the value
specified by ret_val.  
TODO: explain <invert>  
local function is_valid_parameter_value (value, name, possible, ret_val, invert)
if not utilities.is_set (value) then
return ret_val; -- an empty parameter is ok
end  
if (not invert and utilities.in_array (value, possible)) then -- normal; <value> is in <possible> table
return cfg.keywords_xlate[value]; -- return translation of parameter keyword
elseif invert and not utilities.in_array (value, possible) then -- invert; <value> is not in <possible> table
return value; -- return <value> as it is
else
utilities.set_message ('err_invalid_param_val', {name, value}); -- not an allowed value so add error message
return ret_val;
end
end  
----------------------------< T E R M I N A T E _ N A M E _ L I S T >----------------------------------------  
This function terminates a name list (author, contributor, editor) with a separator character (sepc) and a space
when the last character is not a sepc character or when the last three characters are not sepc followed by two
closing square brackets (close of a wikilink). When either of these is true, the name_list is terminated with a
single space character.  
local function terminate_name_list (name_list, sepc)
if (string.sub (name_list, -3, -1) == sepc .. '. ') then -- if already properly terminated
return name_list; -- just return the name list
elseif (string.sub (name_list, -1, -1) == sepc) or (string.sub (name_list, -3, -1) == sepc .. ']]') then -- if last name in list ends with sepc char
return name_list .. " "; -- don't add another
else
return name_list .. sepc .. ' '; -- otherwise terminate the name list
end
end