-- Convert a value from one unit of measurement to another. -- Example:  --> 123 pounds (56 kg) -- See :en:Template:Convert/Transwiki guide if copying to another wiki.  local MINUS = '−'  -- Unicode U+2212 MINUS SIGN (UTF-8: e2 88 92) local abs = math.abs local floor = math.floor local format = string.format local log10 = math.log10 local ustring = mw.ustring local ulen = ustring.len local usub = ustring.sub  -- Configuration options to keep magic values in one location. -- Conversion data and message text are defined in separate modules. local config, maxsigfig local numdot  -- must be '.' or ',' or a character which works in a regex local numsep, numsep_remove, numsep_remove2 local data_code, all_units local text_code local varname        -- can be a code to use variable names that depend on value local from_en_table  -- to translate an output string of en digits to local language local to_en_table    -- to translate an input string of digits in local language to en -- Use translation_table in convert/text to change the following. local en_default           -- true uses lang=en unless convert has lang=local or local digits local group_method = 3     -- code for how many digits are in a group local per_word = 'per'     -- for units like "liters per kilometer" local plural_suffix = 's'  -- only other useful value is probably  to disable plural unit names local omitsep              -- true to omit separator before local symbol/name  -- All units should be defined in the data module. However, to cater for quick changes -- and experiments, any unknown unit is looked up in an extra data module, if it exists. -- That module would be transcluded in only a small number of pages, so there should be -- little server overhead from making changes, and changes should propagate quickly. local extra_module  -- name of module with extra units local extra_units   -- nil or table of extra units from extra_module  -- Some options in the invoking template can set variables used later in the module. local currency_text  -- for a user-defined currency symbol:  (euro replaces dollar)  local function from_en(text) 	-- Input is a string representing a number in en digits with '.' decimal mark, 	-- without digit grouping (which is done just after calling this). 	-- Return the translation of the string with numdot and digits in local language. 	if numdot ~= '.' then 		text = text:gsub('%.', numdot) 	end 	if from_en_table then 		text = text:gsub('%d', from_en_table) 	end 	return text end  local function to_en(text) 	-- Input is a string representing a number in the local language with 	-- an optional numdot decimal mark and numsep digit grouping. 	-- Return the translation of the string with '.' mark and en digits, 	-- and no separators (they have to be removed here to handle cases like 	-- numsep = '.' and numdot = ',' with input "1.234.567,8"). 	if to_en_table then 		text = ustring.gsub(text, '%d', to_en_table) 	end 	if numsep_remove then 		text = text:gsub(numsep_remove, ) 	end 	if numsep_remove2 then 		text = text:gsub(numsep_remove2, ) 	end 	if numdot ~= '.' then 		text = text:gsub(numdot, '.') 	end 	return text end  local function decimal_mark(text) 	-- Return ',' if text probably is using comma for decimal mark, or has no decimal mark. 	-- Return '.' if text probably is using dot for decimal mark. 	-- Otherwise return nothing (decimal mark not known). 	if not text:find('[.,]') then return ',' end 	text = text:gsub('^%-', ):gsub('%+%d+/%d+$', ):gsub('[Ee]%-?%d+$', ) 	local decimal = 		text:match('^0?([.,])%d+$') or 		text:match('%d([.,])%d?%d?$') or 		text:match('%d([.,])%d%d%d%d+$') 	if decimal then return decimal end 	if text:match('%.%d+%.') then return ',' end 	if text:match('%,%d+,') then return '.' end end  local add_warning, with_separator  -- forward declarations local function to_en_with_check(text, parms) 	-- Version of to_en() for a wiki using numdot = ',' and numsep = '.' to check 	-- text (an input number as a string) which might have been copied from enwiki. 	-- For example, in '1.234' the '.' could be a decimal mark or a group separator. 	-- From viwiki. 	if to_en_table then 		text = ustring.gsub(text, '%d', to_en_table) 	end 	if decimal_mark(text) == '.' then 		local original = text 		text = text:gsub(',', )  -- for example, interpret "1,234.5" as an enwiki value 		if parms then 			add_warning(parms, 0, 'cvt_enwiki_num', original, with_separator({}, text)) 		end 	else 		if numsep_remove then 			text = text:gsub(numsep_remove, ) 		end 		if numsep_remove2 then 			text = text:gsub(numsep_remove2, ) 		end 		if numdot ~= '.' then 			text = text:gsub(numdot, '.') 		end 	end 	return text end  local function omit_separator(id) 	-- Return true if there should be no separator before id (a unit symbol or name). 	-- For zhwiki, there should be no separator if id uses local characters. 	-- The following kludge should be a sufficient test. 	if omitsep then 		if id:sub(1, 2) == '-{' then  -- for "-{...}-" content language variant 			return true 		end 		if id:byte() > 127 then 			local first = usub(id, 1, 1) 			if first ~= 'Å' and first ~= '°' and first ~= 'µ' then 				return true 			end 		end 	end 	return id:sub(1, 1) == '/'  -- no separator before units like "/ha" end  local spell_module  -- name of module that can spell numbers local speller       -- function from that module to handle spelling (set if needed) local wikidata_module, wikidata_data_module  -- names of Wikidata modules local wikidata_code, wikidata_data  -- exported tables from those modules (set if needed)  local function set_config(args) 	-- Set configuration options from template #invoke or defaults. 	config = args 	maxsigfig = config.maxsigfig or 14  -- maximum number of significant figures 	local data_module, text_module 	local sandbox = config.sandbox and ('/' .. config.sandbox) or  	data_module = "Module:Convert/data" .. sandbox 	text_module = "Module:Convert/text" .. sandbox 	extra_module = "Module:Convert/extra" .. sandbox 	wikidata_module = "Module:Convert/wikidata" .. sandbox 	wikidata_data_module = "Module:Convert/wikidata/data" .. sandbox 	spell_module = "Module:ConvertNumeric" 	data_code = mw.loadData(data_module) 	text_code = mw.loadData(text_module) 	all_units = data_code.all_units 	local translation = text_code.translation_table 	if translation then 		numdot = translation.numdot 		numsep = translation.numsep 		if numdot == ',' and numsep == '.' then 			if text_code.all_messages.cvt_enwiki_num then 				to_en = to_en_with_check 			end 		end 		if translation.group then 			group_method = translation.group 		end 		if translation.per_word then 			per_word = translation.per_word 		end 		if translation.plural_suffix then 			plural_suffix = translation.plural_suffix 		end 		varname = translation.varname 		from_en_table = translation.from_en 		local use_workaround = true 		if use_workaround then 			-- 2013-07-05 workaround bug by making a copy of the required table. 			-- mw.ustring.gsub fails with a table (to_en_table) as the replacement, 			-- if the table is accessed via mw.loadData. 			local source = translation.to_en 			if source then 				to_en_table = {} 				for k, v in pairs(source) do 					to_en_table[k] = v 				end 			end 		else 			to_en_table = translation.to_en 		end 		if translation.lang == 'en default' then 			en_default = true  -- for hiwiki 		end 		omitsep = translation.omitsep  -- for zhwiki 	end 	numdot = config.numdot or numdot or '.'  -- decimal mark before fractional digits 	numsep = config.numsep or numsep or ','  -- group separator for numbers 	-- numsep should be ',' or '.' or  or ' ' or a Unicode character. 	-- numsep_remove must work in a regex to identify separators to be removed. 	if numsep ~=  then 		numsep_remove = (numsep == '.') and '%.' or numsep 	end 	if numsep ~= ',' and numdot ~= ',' then 		numsep_remove2 = ','  -- so numbers copied from enwiki will work 	end end  local function collection() 	-- Return a table to hold items. 	return { 		n = 0, 		add = function (self, item) 			self.n = self.n + 1 			self[self.n] = item 		end, 	} end  local function divide(numerator, denominator) 	-- Return integers quotient, remainder resulting from dividing the two 	-- given numbers, which should be unsigned integers. 	local quotient, remainder = floor(numerator / denominator), numerator % denominator 	if not (0 <= remainder and remainder < denominator) then 		-- Floating point limits may need this, as in . 		remainder = 0 	end 	return quotient, remainder end  local function split(text, delimiter) 	-- Return a numbered table with fields from splitting text. 	-- The delimiter is used in a regex without escaping (for example, '.' would fail). 	-- Each field has any leading/trailing whitespace removed. 	local t = {} 	text = text .. delimiter  -- to get last item 	for item in text:gmatch('%s*(.-)%s*' .. delimiter) do 		table.insert(t, item) 	end 	return t end  local function strip(text) 	-- If text is a string, return its content with no leading/trailing 	-- whitespace. Otherwise return nil (a nil argument gives a nil result). 	if type(text) == 'string' then 		return text:match("^%s*(.-)%s*$") 	end end  local function table_len(t) 	-- Return length (<100) of a numbered table to replace #t which is 	-- documented to not work if t is accessed via mw.loadData(). 	for i = 1, 100 do 		if t[i] == nil then 			return i - 1 		end 	end end  local function wanted_category(catkey, catsort, want_warning) 	-- Return message category if it is wanted in current namespace, 	-- otherwise return . 	local cat 	local title = mw.title.getCurrentTitle() 	if title then 		local nsdefault = '0'  -- default namespace: '0' = article; '0,10' = article and template 		local namespace = title.namespace 		for _, v in ipairs(split(config.nscat or nsdefault, ',')) do 			if namespace == tonumber(v) then 				cat = text_code.all_categories[want_warning and 'warning' or catkey] 				if catsort and catsort ~=  and cat:sub(-2) == ']]' then 					cat = cat:sub(1, -3) .. '|' .. mw.text.nowiki(usub(catsort, 1, 20)) .. ']]' 				end 				break 			end 		end 	end 	return cat or end  local function message(parms, mcode, is_warning) 	-- Return wikitext for an error message, including category if specified 	-- for the message type. 	-- mcode = numbered table specifying the message: 	--    mcode[1] = 'cvt_xxx' (string used as a key to get message info) 	--    mcode[2] = 'parm1' (string to replace '$1' if any in message) 	--    mcode[3] = 'parm2' (string to replace '$2' if any in message) 	--    mcode[4] = 'parm3' (string to replace '$3' if any in message) 	local msg 	if type(mcode) == 'table' then 		if mcode[1] == 'cvt_no_output' then 			-- Some errors should cause convert to output an empty string, 			-- for example, for an optional field in an infobox. 			return  		end 		msg = text_code.all_messages[mcode[1]] 	end 	parms.have_problem = true 	local function subparm(fmt, ...) 		local rep = {} 		for i, v in ipairs({...}) do 			rep['$' .. i] = v 		end 		return (fmt:gsub('$%d+', rep)) 	end 	if msg then 		local parts = {} 		local regex, replace = msg.regex, msg.replace 		for i = 1, 3 do 			local limit = 40 			local s = mcode[i + 1] 			if s then 				if regex and replace then 					s = s:gsub(regex, replace) 					limit = nil  -- allow long "should be" messages 				end 				-- Escape user input so it does not break the message. 				-- To avoid tags (like ) breaking 				-- the mouseover title, any strip marker starting with char(127) is 				-- replaced with '...' (text not needing i18n). 				local append 				local pos = s:find(string.char(127), 1, true) 				if pos then 					append = '...' 					s = s:sub(1, pos - 1) 				end 				if limit and ulen(s) > limit then 					s = usub(s, 1, limit) 					append = '...' 				end 				s = mw.text.nowiki(s) .. (append or ) 			else 				s = '?' 			end 			parts['$' .. i] = s 		end 		local function ispreview() 			-- Return true if a prominent message should be shown. 			if parms.test == 'preview' or parms.test == 'nopreview' then 				-- For testing, can preview a real message or simulate a preview 				-- when running automated tests. 				return parms.test == 'preview' 			end 			local success, revid = pcall(function () 				return (parms.frame):preprocess('') end) 			return success and (revid == ) 		end 		local want_warning = is_warning and 			not config.warnings and  -- show unobtrusive warnings if config.warnings not configured 			not msg.nowarn           -- but use msg settings, not standard warning, if specified 		local title = string.gsub(msg[1] or 'Missing message', '$%d+', parts) 		local text = want_warning and '*' or msg[2] or 'Missing message' 		local cat = wanted_category(msg[3], mcode[2], want_warning) 		local anchor = msg[4] or 		local fmtkey = ispreview() and 'cvt_format_preview' or 			(want_warning and 'cvt_format2' or msg.format or 'cvt_format') 		local fmt = text_code.all_messages[fmtkey] or 'convert: bug' 		return subparm(fmt, title:gsub('"', '"'), text, cat, anchor) 	end 	return 'Convert internal error: unknown message' end  function add_warning(parms, level, key, text1, text2)  -- for forward declaration above 	-- If enabled, add a warning that will be displayed after the convert result. 	-- A higher level is more verbose: more kinds of warnings are displayed. 	-- To reduce output noise, only the first warning is displayed. 	if level <= (tonumber(config.warnings) or 1) then 		if parms.warnings == nil then 			parms.warnings = message(parms, { key, text1, text2 }, true) 		end 	end end  local function spell_number(parms, inout, number, numerator, denominator) 	-- Return result of spelling (number, numerator, denominator), or 	-- return nil if spelling is not available or not supported for given text. 	-- Examples (each value must be a string or nil): 	--   number  numerator  denominator  output 	--   ------  ---------  -----------  ------------------- 	--   "1.23"    nil        nil        one point two three 	--    "1"      "2"        "3"        one and two thirds 	--    nil      "2"        "3"        two thirds 	if not speller then 		local function get_speller(module) 			return require(module).spell_number 		end 		local success 		success, speller = pcall(get_speller, spell_module) 		if not success or type(speller) ~= 'function' then 			add_warning(parms, 1, 'cvt_no_spell', 'spell') 			return nil 		end 	end 	local case 	if parms.spell_upper == inout then 		case = true 		parms.spell_upper = nil  -- only uppercase first word in a multiple unit 	end 	local sp = not parms.opt_sp_us 	local adj = parms.opt_adjectival 	return speller(number, numerator, denominator, case, sp, adj) end  -- BEGIN: Code required only for built-in units. -- LATER: If need much more code, move to another module to simplify this module. local function speed_of_sound(altitude) 	-- This is for the Mach built-in unit of speed. 	-- Return speed of sound in metres per second at given altitude in feet. 	-- If no altitude given, use default (zero altitude = sea level). 	-- Table gives speed of sound in miles per hour at various altitudes: 	--   altitude = -17,499 to 302,499 feet 	-- mach_table[a + 4] = s where 	--   a = (altitude / 5000) rounded to nearest integer (-3 to 60) 	--   s = speed of sound (mph) at that altitude 	-- LATER: Should calculate result from an interpolation between the next 	-- lower and higher altitudes in table, rather than rounding to nearest. 	-- From: http://www.aerospaceweb.org/question/atmosphere/q0112.shtml 	local mach_table = {                                                       -- a = 		799.5, 787.0, 774.2, 761.207051,                                       -- -3 to  0 		748.0, 734.6, 721.0, 707.0, 692.8, 678.3, 663.5, 660.1, 660.1, 660.1,  --  1 to 10 		660.1, 660.1, 660.1, 662.0, 664.3, 666.5, 668.9, 671.1, 673.4, 675.6,  -- 11 to 20 		677.9, 683.7, 689.9, 696.0, 702.1, 708.1, 714.0, 719.9, 725.8, 731.6,  -- 21 to 30 		737.3, 737.7, 737.7, 736.2, 730.5, 724.6, 718.8, 712.9, 707.0, 701.1,  -- 31 to 40 		695.0, 688.9, 682.8, 676.6, 670.4, 664.1, 657.8, 652.9, 648.3, 643.7,  -- 41 to 50 		639.1, 634.4, 629.6, 624.8, 620.0, 615.2, 613.2, 613.2, 613.2, 613.5,  -- 51 to 60 	} 	altitude = altitude or 0 	local a = (altitude < 0) and -altitude or altitude 	a = floor(a / 5000 + 0.5) 	if altitude < 0 then 		a = -a 	end 	if a < -3 then 		a = -3 	elseif a > 60 then 		a = 60 	end 	return mach_table[a + 4] * 0.44704  -- mph converted to m/s end -- END: Code required only for built-in units.  local function add_style(parms, class) 	-- Add selected template style to parms if not already present. 	parms.templatestyles = parms.templatestyles or {} 	if not parms.templatestyles[class] then 		parms.templatestyles[class] = parms.frame:extensionTag({ 			name = 'templatestyles', args = { src = text_code.titles[class] } 		}) 	end end  local function get_styles(parms) 	-- Return string of required template styles, empty if none. 	if parms.templatestyles then 		local t = {} 		for _, v in pairs(parms.templatestyles) do 			table.insert(t, v) 		end 		return table.concat(t) 	end 	return  end  local function get_range(word) 	-- Return a range (string or table) corresponding to word (like "to"), 	-- or return nil if not a range word. 	local ranges = text_code.ranges 	return ranges.types[word] or ranges.types[ranges.aliases[word]] end  local function check_mismatch(unit1, unit2) 	-- If unit1 cannot be converted to unit2, return an error message table. 	-- This allows conversion between units of the same type, and between 	-- Nm (normally torque) and ftlb (energy), as in gun-related articles. 	-- This works because Nm is the base unit (scale = 1) for both the 	-- primary type (torque), and the alternate type (energy, where Nm = J). 	-- A match occurs if the primary types are the same, or if unit1 matches 	-- the alternate type of unit2, and vice versa. That provides a whitelist 	-- of which conversions are permitted between normally incompatible types. 	if unit1.utype == unit2.utype or 		(unit1.utype == unit2.alttype and unit1.alttype == unit2.utype) then 		return nil 	end 	return { 'cvt_mismatch', unit1.utype, unit2.utype } end  local function override_from(out_table, in_table, fields) 	-- Copy the specified fields from in_table to out_table, but do not 	-- copy nil fields (keep any corresponding field in out_table). 	for _, field in ipairs(fields) do 		if in_table[field] then 			out_table[field] = in_table[field] 		end 	end end  local function shallow_copy(t) 	-- Return a shallow copy of table t. 	-- Do not need the features and overhead of the Scribunto mw.clone(). 	local result = {} 	for k, v in pairs(t) do 		result[k] = v 	end 	return result end  local unit_mt = { 	-- Metatable to get missing values for a unit that does not accept SI prefixes. 	-- Warning: The boolean value 'false' is returned for any missing field 	-- so __index is not called twice for the same field in a given unit. 	__index = function (self, key) 		local value 		if key == 'name1' or key == 'sym_us' then 			value = self.symbol 		elseif key == 'name2' then 			value = self.name1 .. plural_suffix 		elseif key == 'name1_us' then 			value = self.name1 			if not rawget(self, 'name2_us') then 				-- If name1_us is 'foot', do not make name2_us by appending plural_suffix. 				self.name2_us = self.name2 			end 		elseif key == 'name2_us' then 			local raw1_us = rawget(self, 'name1_us') 			if raw1_us then 				value = raw1_us .. plural_suffix 			else 				value = self.name2 			end 		elseif key == 'link' then 			value = self.name1 		else 			value = false 		end 		rawset(self, key, value) 		return value 	end }  local function prefixed_name(unit, name, index) 	-- Return unit name with SI prefix inserted at correct position. 	-- index = 1 (name1), 2 (name2), 3 (name1_us), 4 (name2_us). 	-- The position is a byte (not character) index, so use Lua's sub(). 	local pos = rawget(unit, 'prefix_position') 	if type(pos) == 'string' then 		pos = tonumber(split(pos, ',')[index]) 	end 	if pos then 		return name:sub(1, pos - 1) .. unit.si_name .. name:sub(pos) 	end 	return unit.si_name .. name end  local unit_prefixed_mt = { 	-- Metatable to get missing values for a unit that accepts SI prefixes. 	-- Before use, fields si_name, si_prefix must be defined. 	-- The unit must define _symbol, _name1 and 	-- may define _sym_us, _name1_us, _name2_us 	-- (_sym_us, _name2_us may be defined for a language using sp=us 	-- to refer to a variant unrelated to U.S. units). 	__index = function (self, key) 		local value 		if key == 'symbol' then 			value = self.si_prefix .. self._symbol 		elseif key == 'sym_us' then 			value = rawget(self, '_sym_us') 			if value then 				value = self.si_prefix .. value 			else 				value = self.symbol 			end 		elseif key == 'name1' then 			value = prefixed_name(self, self._name1, 1) 		elseif key == 'name2' then 			value = rawget(self, '_name2') 			if value then 				value = prefixed_name(self, value, 2) 			else 				value = self.name1 .. plural_suffix 			end 		elseif key == 'name1_us' then 			value = rawget(self, '_name1_us') 			if value then 				value = prefixed_name(self, value, 3) 			else 				value = self.name1 			end 		elseif key == 'name2_us' then 			value = rawget(self, '_name2_us') 			if value then 				value = prefixed_name(self, value, 4) 			elseif rawget(self, '_name1_us') then 				value = self.name1_us .. plural_suffix 			else 				value = self.name2 			end 		elseif key == 'link' then 			value = self.name1 		else 			value = false 		end 		rawset(self, key, value) 		return value 	end }  local unit_per_mt = { 	-- Metatable to get values for a per unit of form "x/y". 	-- This is never called to determine a unit name or link because per units 	-- are handled as a special case. 	-- Similarly, the default output is handled elsewhere, and for a symbol 	-- this is only called from get_default() for default_exceptions. 	__index = function (self, key) 		local value 		if key == 'symbol' then 			local per = self.per 			local unit1, unit2 = per[1], per[2] 			if unit1 then 				value = unit1[key] .. '/' .. unit2[key] 			else 				value = '/' .. unit2[key] 			end 		elseif key == 'sym_us' then 			value = self.symbol 		elseif key == 'scale' then 			local per = self.per 			local unit1, unit2 = per[1], per[2] 			value = (unit1 and unit1.scale or 1) * self.scalemultiplier / unit2.scale 		else 			value = false 		end 		rawset(self, key, value) 		return value 	end }  local function make_per(unitcode, unit_table, ulookup) 	-- Return true, t where t is a per unit with unit codes expanded to unit tables, 	-- or return false, t where t is an error message table. 	local result = { 		unitcode = unitcode, 		utype = unit_table.utype, 		per = {} 	} 	override_from(result, unit_table, { 'invert', 'iscomplex', 'default', 'link', 'symbol', 'symlink' }) 	result.symbol_raw = (result.symbol or false)  -- to distinguish between a defined exception and a metatable calculation 	local prefix 	for i, v in ipairs(unit_table.per) do 		if i == 1 and v ==  then 			-- First unit symbol can be empty; that gives a nil first unit table. 		elseif i == 1 and text_code.currency[v] then 			prefix = currency_text or v 		else 			local success, t = ulookup(v) 			if not success then return false, t end 			result.per[i] = t 		end 	end 	local multiplier = unit_table.multiplier 	if not result.utype then 		-- Creating an automatic per unit. 		local unit1 = result.per[1] 		local utype = (unit1 and unit1.utype or prefix or ) .. '/' .. result.per[2].utype 		local t = data_code.per_unit_fixups[utype] 		if t then 			if type(t) == 'table' then 				utype = t.utype or utype 				result.link = result.link or t.link 				multiplier = multiplier or t.multiplier 			else 				utype = t 			end 		end 		result.utype = utype 	end 	result.scalemultiplier = multiplier or 1 	result.vprefix = prefix or false  -- set to non-nil to avoid calling __index 	return true, setmetatable(result, unit_per_mt) end  local function lookup(parms, unitcode, what, utable, fails, depth) 	-- Return true, t where t is a copy of the unit's converter table, 	-- or return false, t where t is an error message table. 	-- Parameter 'what' determines whether combination units are accepted: 	--   'no_combination'  : single unit only 	--   'any_combination' : single unit or combination or output multiple 	--   'only_multiple'   : single unit or output multiple only 	-- Parameter unitcode is a symbol (like 'g'), with an optional SI prefix (like 'kg'). 	-- If, for example, 'kg' is in this table, that entry is used; 	-- otherwise the prefix ('k') is applied to the base unit ('g'). 	-- If unitcode is a known combination code (and if allowed by what), 	-- a table of output multiple unit tables is included in the result. 	-- For compatibility with the old template, an underscore in a unitcode is 	-- replaced with a space so usage like  works. 	-- Wikignomes may also put two spaces or " " in combinations, so 	-- replace underscore, " ", and multiple spaces with a single space. 	utable = utable or parms.unittable or all_units 	fails = fails or {} 	depth = depth and depth + 1 or 1 	if depth > 9 then 		-- There are ways to mistakenly define units which result in infinite 		-- recursion when lookup() is called. That gives a long delay and very 		-- confusing error messages, so the depth parameter is used as a guard. 		return false, { 'cvt_lookup', unitcode } 	end 	if unitcode == nil or unitcode ==  then 		return false, { 'cvt_no_unit' } 	end 	unitcode = unitcode:gsub('_', ' '):gsub(' ', ' '):gsub('  +', ' ') 	local function call_make_per(t) 		return make_per(unitcode, t, 			function (ucode) return lookup(parms, ucode, 'no_combination', utable, fails, depth) end 		) 	end 	local t = utable[unitcode] 	if t then 		if t.shouldbe then 			return false, { 'cvt_should_be', t.shouldbe } 		end 		if t.sp_us then 			parms.opt_sp_us = true 		end 		local target = t.target  -- nil, or unitcode is an alias for this target 		if target then 			local success, result = lookup(parms, target, what, utable, fails, depth) 			if not success then return false, result end 			override_from(result, t, { 'customary', 'default', 'link', 'symbol', 'symlink' }) 			local multiplier = t.multiplier 			if multiplier then 				result.multiplier = tostring(multiplier) 				result.scale = result.scale * multiplier 			end 			return true, result 		end 		if t.per then 			return call_make_per(t) 		end 		local combo = t.combination  -- nil or a table of unitcodes 		if combo then 			local multiple = t.multiple 			if what == 'no_combination' or (what == 'only_multiple' and not multiple) then 				return false, { 'cvt_bad_unit', unitcode } 			end 			-- Recursively create a combination table containing the 			-- converter table of each unitcode. 			local result = { utype = t.utype, multiple = multiple, combination = {} } 			local cvt = result.combination 			for i, v in ipairs(combo) do 				local success, t = lookup(parms, v, multiple and 'no_combination' or 'only_multiple', utable, fails, depth) 				if not success then return false, t end 				cvt[i] = t 			end 			return true, result 		end 		local result = shallow_copy(t) 		result.unitcode = unitcode 		if result.prefixes then 			result.si_name =  			result.si_prefix = 			return true, setmetatable(result, unit_prefixed_mt) 		end 		return true, setmetatable(result, unit_mt) 	end 	local SIprefixes = text_code.SIprefixes 	for plen = SIprefixes[1] or 2, 1, -1 do 		-- Look for an SI prefix; should never occur with an alias. 		-- Check for longer prefix first ('dam' is decametre). 		-- SIprefixes[1] = prefix maximum #characters (as seen by mw.ustring.sub). 		local prefix = usub(unitcode, 1, plen) 		local si = SIprefixes[prefix] 		if si then 			local t = utable[usub(unitcode, plen+1)] 			if t and t.prefixes then 				local result = shallow_copy(t) 				result.unitcode = unitcode 				result.si_name = parms.opt_sp_us and si.name_us or si.name 				result.si_prefix = si.prefix or prefix 				result.scale = t.scale * 10 ^ (si.exponent * t.prefixes) 				return true, setmetatable(result, unit_prefixed_mt) 			end 		end 	end 	-- Accept user-defined combinations like "acre+m2+ha" or "acre m2 ha" for output. 	-- If '+' is used, each unit code can include a space, and any error is fatal. 	-- If ' ' is used and if each space-separated word is a unit code, it is a combo, 	-- but errors are not fatal so the unit code can be looked up as an extra unit. 	local err_is_fatal 	local combo = collection() 	if unitcode:find('+', 1, true) then 		err_is_fatal = true 		for item in (unitcode .. '+'):gmatch('%s*(.-)%s*%+') do 			if item ~=  then 				combo:add(item) 			end 		end 	elseif unitcode:find('%s') then 		for item in unitcode:gmatch('%S+') do 			combo:add(item) 		end 	end 	if combo.n > 1 then 		local function lookup_combo() 			if what == 'no_combination' or what == 'only_multiple' then 				return false, { 'cvt_bad_unit', unitcode } 			end 			local result = { combination = {} } 			local cvt = result.combination 			for i, v in ipairs(combo) do 				local success, t = lookup(parms, v, 'only_multiple', utable, fails, depth) 				if not success then return false, t end 				if i == 1 then 					result.utype = t.utype 				else 					local mismatch = check_mismatch(result, t) 					if mismatch then 						return false, mismatch 					end 				end 				cvt[i] = t 			end 			return true, result 		end 		local success, result = lookup_combo() 		if success or err_is_fatal then 			return success, result 		end 	end 	-- Accept any unit with an engineering notation prefix like "e6cuft" 	-- (million cubic feet), but not chained prefixes like "e3e6cuft", 	-- and not if the unit is a combination or multiple, 	-- and not if the unit has an offset or is a built-in. 	-- Only en digits are accepted. 	local exponent, baseunit = unitcode:match('^e(%d+)(.*)') 	if exponent then 		local engscale = text_code.eng_scales[exponent] 		if engscale then 			local success, result = lookup(parms, baseunit, 'no_combination', utable, fails, depth) 			if success and not (result.offset or result.builtin or result.engscale) then 				result.unitcode = unitcode  -- 'e6cuft' not 'cuft' 				result.defkey = unitcode  -- key to lookup default exception 				result.engscale = engscale 				result.scale = result.scale * 10 ^ tonumber(exponent) 				return true, result 			end 		end 	end 	-- Look for x/y; split on right-most slash to get scale correct (x/y/z is x/y per z). 	local top, bottom = unitcode:match('^(.-)/([^/]+)$') 	if top and not unitcode:find('e%d') then 		-- If valid, create an automatic per unit for an "x/y" unit code. 		-- The unitcode must not include extraneous spaces. 		-- Engineering notation (apart from at start and which has been stripped before here), 		-- is not supported so do not make a per unit if find text like 'e3' in unitcode. 		local success, result = call_make_per({ per = {top, bottom} }) 		if success then 			return true, result 		end 	end 	if not parms.opt_ignore_error and not get_range(unitcode) then 		-- Want the "what links here" list for the extra_module to show only cases 		-- where an extra unit is used, so do not require it if invoked from  		-- or if looking up a range word which cannot be a unit. 		if not extra_units then 			local success, extra = pcall(function () return require(extra_module).extra_units end) 			if success and type(extra) == 'table' then 				extra_units = extra 			end 		end 		if extra_units then 			-- A unit in one data table might refer to a unit in the other table, so 			-- switch between them, relying on fails or depth to terminate loops. 			if not fails[unitcode] then 				fails[unitcode] = true 				local other = (utable == all_units) and extra_units or all_units 				local success, result = lookup(parms, unitcode, what, other, fails, depth) 				if success then 					return true, result 				end 			end 		end 	end 	if to_en_table then 		-- At fawiki it is common to translate all digits so a unit like "km2" becomes "km۲". 		local en_code = ustring.gsub(unitcode, '%d', to_en_table) 		if en_code ~= unitcode then 			return lookup(parms, en_code, what, utable, fails, depth) 		end 	end 	return false, { 'cvt_unknown', unitcode } end  local function valid_number(num) 	-- Return true if num is a valid number. 	-- In Scribunto (different from some standard Lua), when expressed as a string, 	-- overflow or other problems are indicated with text like "inf" or "nan" 	-- which are regarded as invalid here (each contains "n"). 	if type(num) == 'number' and tostring(num):find('n', 1, true) == nil then 		return true 	end end  local function hyphenated(name, parts) 	-- Return a hyphenated form of given name (for adjectival usage). 	-- The name may be linked and the target of the link must not be changed. 	-- Hypothetical examples: 	--   ton         →  ton          (no change) 	--   long ton       →  long-ton 	--   long ton  →  long-ton 	--   long ton             →  long-ton 	-- Input can also have multiple links in a single name like: 	--   U.S. gallon 	--   miles per U.S. quart 	--   long tons per short ton 	-- Assume that links cannot be nested (never like "[[abcdefghi]]"). 	-- This uses a simple and efficient procedure that works for most cases. 	-- Some units (if used) would require more, and can later think about 	-- adding a method to handle exceptions. 	-- The procedure is to replace each space with a hyphen, but 	-- not a space after ')' [for "(pre-1954 US) nautical mile"], and 	-- not spaces immediately before '(' or in '(...)' [for cases like 	-- "British thermal unit (ISO)" and "Calorie (International Steam Table)"]. 	if name:find(' ', 1, true) then 		if parts then 			local pos 			if name:sub(1, 1) == '(' then 				pos = name:find(')', 1, true) 				if pos then 					return name:sub(1, pos+1) .. name:sub(pos+2):gsub(' ', '-') 				end 			elseif name:sub(-1) == ')' then 				pos = name:find('(', 1, true) 				if pos then 					return name:sub(1, pos-2):gsub(' ', '-') .. name:sub(pos-1) 				end 			end 			return name:gsub(' ', '-') 		end 		parts = collection() 		for before, item, after in name:gmatch('([^[]*)(%[%[[^[]*%]%])([^[]*)') do 			if item:find(' ', 1, true) then 				local prefix 				local plen = item:find('|', 1, true) 				if plen then 					prefix = item:sub(1, plen) 					item = item:sub(plen + 1, -3) 				else 					prefix = item:sub(1, -3) .. '|' 					item = item:sub(3, -3) 				end 				item = prefix .. hyphenated(item, parts) .. ']]' 			end 			parts:add(before:gsub(' ', '-') .. item .. after:gsub(' ', '-')) 		end 		if parts.n == 0 then 			-- No link like "..." was found in the original name. 			parts:add(hyphenated(name, parts)) 		end 		return table.concat(parts) 	end 	return name end  local function hyphenated_maybe(parms, want_name, sep, id, inout) 	-- Return s, f where 	--   s = id, possibly modified 	--   f = true if hyphenated 	-- Possible modifications: hyphenate; prepend '-'; append mid text. 	if id == nil or id ==  then 		return  	end 	local mid = (inout == (parms.opt_flip and 'out' or 'in')) and parms.mid or 	if want_name then 		if parms.opt_adjectival then 			return '-' .. hyphenated(id) .. mid, true 		end 		if parms.opt_add_s and id:sub(-1) ~= 's' then 			id = id .. 's'  -- for nowiki 		end 	end 	return sep .. id .. mid end  local function use_minus(text) 	-- Return text with Unicode minus instead of '-', if present. 	if text:sub(1, 1) == '-' then 		return MINUS .. text:sub(2) 	end 	return text end  local function digit_groups(parms, text, method) 	-- Return a numbered table of groups of digits (left-to-right, in local language). 	-- Parameter method is a number or nil: 	--   3 for 3-digit grouping (default), or 	--   2 for 3-then-2 grouping (only for digits before decimal mark). 	local len_right 	local len_left = text:find('.', 1, true) 	if len_left then 		len_right = #text - len_left 		len_left = len_left - 1 	else 		len_left = #text 	end 	local twos = method == 2 and len_left > 5 	local groups = collection() 	local run = len_left 	local n 	if run < 4 or (run == 4 and parms.opt_comma5) then 		if parms.opt_gaps then 			n = run 		else 			n = #text 		end 	elseif twos then 		n = run % 2 == 0 and 1 or 2 	else 		n = run % 3 == 0 and 3 or run % 3 	end 	while run > 0 do 		groups:add(n) 		run = run - n 		n = (twos and run > 3) and 2 or 3 	end 	if len_right then 		if groups.n == 0 then 			groups:add(0) 		end 		if parms.opt_gaps and len_right > 3 then 			local want4 = not parms.opt_gaps3  -- true gives no gap before trailing single digit 			local isfirst = true 			run = len_right 			while run > 0 do 				n = (want4 and run == 4) and 4 or (run > 3 and 3 or run) 				if isfirst then 					isfirst = false 					groups[groups.n] = groups[groups.n] + 1 + n 				else 					groups:add(n) 				end 				run = run - n 			end 		else 			groups[groups.n] = groups[groups.n] + 1 + len_right 		end 	end 	local pos = 1 	for i, length in ipairs(groups) do 		groups[i] = from_en(text:sub(pos, pos + length - 1)) 		pos = pos + length 	end 	return groups end  function with_separator(parms, text)  -- for forward declaration above 	-- Input text is a number in en digits with optional '.' decimal mark. 	-- Return an equivalent, formatted for display: 	--   with a custom decimal mark instead of '.', if wanted 	--   with thousand separators inserted, if wanted 	--   digits in local language 	-- The given text is like '123' or '123.' or '12345.6789'. 	-- The text has no sign (caller inserts that later, if necessary). 	-- When using gaps, they are inserted before and after the decimal mark. 	-- Separators are inserted only before the decimal mark. 	-- A trailing dot (as in '123.') is removed because their use appears to 	-- be accidental, and such a number should be shown as '123' or '123.0'. 	-- It is useful for convert to suppress the dot so, for example, '4000.' 	-- is a simple way of indicating that all the digits are significant. 	if text:sub(-1) == '.' then 		text = text:sub(1, -2) 	end 	if #text < 4 or parms.opt_nocomma or numsep ==  then 		return from_en(text) 	end 	local groups = digit_groups(parms, text, group_method) 	if parms.opt_gaps then 		if groups.n <= 1 then 			return groups[1] or 		end 		local nowrap = '<span style="white-space: nowrap">' 		local gap = '' 		local close = '' 		return nowrap .. groups[1] .. gap .. table.concat(groups, close .. gap, 2, groups.n) .. close .. close 	end 	return table.concat(groups, numsep) end  -- An input value like 1.23e12 is displayed using scientific notation (1.23×10¹²). -- That also makes the output use scientific notation, except for small values. -- In addition, very small or very large output values use scientific notation. -- Use format(fmtpower, significand, '10', exponent) where each argument is a string. local fmtpower = '%s×%s%s'  local function with_exponent(parms, show, exponent) 	-- Return wikitext to display the implied value in scientific notation. 	-- Input uses en digits; output uses digits in local language. 	return format(fmtpower, with_separator(parms, show), from_en('10'), use_minus(from_en(tostring(exponent)))) end  local function make_sigfig(value, sigfig) 	-- Return show, exponent that are equivalent to the result of 	-- converting the number 'value' (where value >= 0) to a string, 	-- rounded to 'sigfig' significant figures. 	-- The returned items are: 	--   show: a string of digits; no sign and no dot; 	--         there is an implied dot before show. 	--   exponent: a number (an integer) to shift the implied dot. 	-- Resulting value = tonumber('.' .. show) * 10^exponent. 	-- Examples: 	--   make_sigfig(23.456, 3) returns '235', 2 (.235 * 10^2). 	--   make_sigfig(0.0023456, 3) returns '235', -2 (.235 * 10^-2). 	--   make_sigfig(0, 3) returns '000', 1 (.000 * 10^1). 	if sigfig <= 0 then 		sigfig = 1 	elseif sigfig > maxsigfig then 		sigfig = maxsigfig 	end 	if value == 0 then 		return string.rep('0', sigfig), 1 	end 	local exp, fracpart = math.modf(log10(value)) 	if fracpart >= 0 then 		fracpart = fracpart - 1 		exp = exp + 1 	end 	local digits = format('%.0f', 10^(fracpart + sigfig)) 	if #digits > sigfig then 		-- Overflow (for sigfig=3: like 0.9999 rounding to "1000"; need "100"). 		digits = digits:sub(1, sigfig) 		exp = exp + 1 	end 	assert(#digits == sigfig, 'Bug: rounded number has wrong length') 	return digits, exp end  -- Fraction output format. local fracfmt = { 	{ -- Like  (fraction slash). 		'{SIGN}{NUM}⁄{DEN}',  -- 1/2 		'{SIGN}{WHOLE}+{NUM}⁄{DEN}',  -- 1+2/3 		style = 'frac', 	}, 	{ -- Like  (stacked fraction, that is, horizontal bar). 		'{SIGN}{NUM}/{DEN}',  -- 1//2 		'{SIGN}{WHOLE}+{NUM}/{DEN}',  -- 1+2//3 		style = 'sfrac', 	}, }  local function format_fraction(parms, inout, negative, wholestr, numstr, denstr, do_spell, style) 	-- Return wikitext for a fraction, possibly spelled. 	-- Inputs use en digits and have no sign; output uses digits in local language. 	local wikitext 	if not style then 		style = parms.opt_fraction_horizontal and 2 or 1 	end 	if wholestr ==  then 		wholestr = nil 	end 	local substitute = { 		SIGN = negative and MINUS or , 		WHOLE = wholestr and with_separator(parms, wholestr), 		NUM = from_en(numstr), 		DEN = from_en(denstr), 	} 	wikitext = fracfmt[style][wholestr and 2 or 1]:gsub('{(%u+)}', substitute) 	if do_spell then 		if negative then 			if wholestr then 				wholestr = '-' .. wholestr 			else 				numstr = '-' .. numstr 			end 		end 		local s = spell_number(parms, inout, wholestr, numstr, denstr) 		if s then 			return s 		end 	end 	add_style(parms, fracfmt[style].style) 	return wikitext end  local function format_number(parms, show, exponent, isnegative) 	-- Parameter show is a string or a table containing strings. 	-- Each string is a formatted number in en digits and optional '.' decimal mark. 	-- A table represents a fraction: integer, numerator, denominator; 	-- if a table is given, exponent must be nil. 	-- Return t where t is a table with fields: 	--   show = wikitext formatted to display implied value 	--          (digits in local language) 	--   is_scientific = true if show uses scientific notation 	--   clean = unformatted show (possibly adjusted and with inserted '.') 	--          (en digits) 	--   sign =  or MINUS 	--   exponent = exponent (possibly adjusted) 	-- The clean and exponent fields can be used to calculate the 	-- rounded absolute value, if needed. 	-- 	-- The value implied by the arguments is found from: 	--   exponent is nil; and 	--   show is a string of digits (no sign), with an optional dot; 	--   show = '123.4' is value 123.4, '1234' is value 1234.0; 	-- or: 	--   exponent is an integer indicating where dot should be; 	--   show is a string of digits (no sign and no dot); 	--   there is an implied dot before show; 	--   show does not start with '0'; 	--   show = '1234', exponent = 3 is value 0.1234*10^3 = 123.4. 	-- 	-- The formatted result: 	-- * Is for an output value and is spelled if wanted and possible. 	-- * Includes a Unicode minus if isnegative and not spelled. 	-- * Uses a custom decimal mark, if wanted. 	-- * Has digits grouped where necessary, if wanted. 	-- * Uses scientific notation if requested, or for very small or large values 	--   (which forces result to not be spelled). 	-- * Has no more than maxsigfig significant digits 	--   (same as old template and ). 	local xhi, xlo  -- these control when scientific notation (exponent) is used 	if parms.opt_scientific then 		xhi, xlo = 4, 2  -- default for output if input uses e-notation 	elseif parms.opt_scientific_always then 		xhi, xlo = 0, 0  -- always use scientific notation (experimental) 	else 		xhi, xlo = 10, 4  -- default 	end 	local sign = isnegative and MINUS or 	local maxlen = maxsigfig 	local tfrac 	if type(show) == 'table' then 		tfrac = show 		show = tfrac.wholestr 		assert(exponent == nil, 'Bug: exponent given with fraction') 	end 	if not tfrac and not exponent then 		local integer, dot, decimals = show:match('^(%d*)(%.?)(.*)') 		if integer == '0' or integer ==  then 			local zeros, figs = decimals:match('^(0*)([^0]?.*)') 			if #figs == 0 then 				if #zeros > maxlen then 					show = '0.' .. zeros:sub(1, maxlen) 				end 			elseif #zeros >= xlo then 				show = figs 				exponent = -#zeros 			elseif #figs > maxlen then 				show = '0.' .. zeros .. figs:sub(1, maxlen) 			end 		elseif #integer >= xhi then 			show = integer .. decimals 			exponent = #integer 		else 			maxlen = maxlen + #dot 			if #show > maxlen then 				show = show:sub(1, maxlen) 			end 		end 	end 	if exponent then 		local function zeros(n) 			return string.rep('0', n) 		end 		if #show > maxlen then 			show = show:sub(1, maxlen) 		end 		if exponent > xhi or exponent <= -xlo or (exponent == xhi and show ~= '1' .. zeros(xhi - 1)) then 			-- When xhi, xlo = 10, 4 (the default), scientific notation is used if the 			-- rounded value satisfies: value >= 1e9 or value < 1e-4 (1e9 = 0.1e10), 			-- except if show is '1000000000' (1e9), for example: 			--  → 1,000,000,000 metres (1,000,000,000 m) 			local significand 			if #show > 1 then 				significand = show:sub(1, 1) .. '.' .. show:sub(2) 			else 				significand = show 			end 			return { 				clean = '.' .. show, 				exponent = exponent, 				sign = sign, 				show = sign .. with_exponent(parms, significand, exponent-1), 				is_scientific = true, 			} 		end 		if exponent >= #show then 			show = show .. zeros(exponent - #show)  -- result has no dot 		elseif exponent <= 0 then 			show = '0.' .. zeros(-exponent) .. show 		else 			show = show:sub(1, exponent) .. '.' .. show:sub(exponent+1) 		end 	end 	local formatted_show 	if tfrac then 		show = tostring(tfrac.value)  -- to set clean in returned table 		formatted_show = format_fraction(parms, 'out', isnegative, tfrac.wholestr, tfrac.numstr, tfrac.denstr, parms.opt_spell_out) 	else 		if isnegative and show:match('^0.?0*$') then 			sign =   -- don't show minus if result is negative but rounds to zero 		end 		formatted_show = sign .. with_separator(parms, show) 		if parms.opt_spell_out then 			formatted_show = spell_number(parms, 'out', sign .. show) or formatted_show 		end 	end 	return { 		clean = show, 		sign = sign, 		show = formatted_show, 		is_scientific = false,  -- to avoid calling __index 	} end  local function extract_fraction(parms, text, negative) 	-- If text represents a fraction, return 	--   value, altvalue, show, denominator 	-- where 	--   value is a number (value of the fraction in argument text) 	--   altvalue is an alternate interpretation of any fraction for the hands 	--        unit where "12.1+3/4" means 12 hands 1.75 inches 	--   show is a string (formatted text for display of an input value, 	--        and is spelled if wanted and possible) 	--   denominator is value of the denominator in the fraction 	-- Otherwise, return nil. 	-- Input uses en digits and '.' decimal mark (input has been translated). 	-- Output uses digits in local language and local decimal mark, if any. 	------------------------------------------------------------------------ 	-- Originally this function accepted x+y/z where x, y, z were any valid 	-- numbers, possibly with a sign. For example '1.23e+2+1.2/2.4' = 123.5, 	-- and '2-3/8' = 1.625. However, such usages were found to be errors or 	-- misunderstandings, so since August 2014 the following restrictions apply: 	--   x (if present) is an integer or has a single digit after decimal mark 	--   y and z are unsigned integers 	--   e-notation is not accepted 	-- The overall number can start with '+' or '-' (so '12+3/4' and '+12+3/4' 	-- and '-12-3/4' are valid). 	-- Any leading negative sign is removed by the caller, so only inputs 	-- like the following are accepted here (may have whitespace): 	--   negative = false       false        true (there was a leading '-') 	--   text     = '2/3'       '+2/3'       '2/3' 	--   text     = '1+2/3'     '+1+2/3'     '1-2/3' 	--   text     = '12.3+1/2'  '+12.3+1/2'  '12.3-1/2' 	-- Values like '12.3+1/2' are accepted, but are intended only for use 	-- with the hands unit (not worth adding code to enforce that). 	------------------------------------------------------------------------ 	local leading_plus, prefix, numstr, slashes, denstr = 		text:match('^%s*(%+?)%s*(.-)%s*(%d+)%s*(/+)%s*(%d+)%s*$') 	if not leading_plus then 		-- Accept a single U+2044 fraction slash because that may be pasted. 		leading_plus, prefix, numstr, denstr = 			text:match('^%s*(%+?)%s*(.-)%s*(%d+)%s*⁄%s*(%d+)%s*$') 		slashes = '/' 	end 	local numerator = tonumber(numstr) 	local denominator = tonumber(denstr) 	if numerator == nil or denominator == nil or (negative and leading_plus ~= ) then 		return nil 	end 	local whole, wholestr 	if prefix ==  then 		wholestr =  		whole = 0 	else 		-- Any prefix must be like '12+' or '12-' (whole number and fraction sign); 		-- '12.3+' and '12.3-' are also accepted (single digit after decimal point) 		-- because '12.3+1/2 hands' is valid (12 hands 3½ inches). 		local num1, num2, frac_sign = prefix:match('^(%d+)(%.?%d?)%s*([+%-])$') 		if num1 == nil then return nil end 		if num2 ==  then  -- num2 must be  or like '.1' but not '.' or '.12' 			wholestr = num1 		else 			if #num2 ~= 2 then return nil end 			wholestr = num1 .. num2 		end 		if frac_sign ~= (negative and '-' or '+') then return nil end 		whole = tonumber(wholestr) 		if whole == nil then return nil end 	end 	local value = whole + numerator / denominator 	if not valid_number(value) then return nil end 	local altvalue = whole + numerator / (denominator * 10) 	local style = #slashes  -- kludge: 1 or 2 slashes can be used to select style 	if style > 2 then style = 2 end 	local wikitext = format_fraction(parms, 'in', negative, leading_plus .. wholestr, numstr, denstr, parms.opt_spell_in, style) 	return value, altvalue, wikitext, denominator end  local function extract_number(parms, text, another, no_fraction) 	-- Return true, info if can extract a number from text, 	-- where info is a table with the result, 	-- or return false, t where t is an error message table. 	-- Input can use en digits or digits in local language and can 	-- have references at the end. Accepting references is intended 	-- for use in infoboxes with a field for a value passed to convert. 	-- Parameter another = true if the expected value is not the first. 	-- Before processing, the input text is cleaned: 	-- * Any thousand separators (valid or not) are removed. 	-- * Any sign is replaced with '-' (if negative) or  (otherwise). 	--   That replaces Unicode minus with '-'. 	-- If successful, the returned info table contains named fields: 	--   value    = a valid number 	--   altvalue = a valid number, usually same as value but different 	--              if fraction used (for hands unit) 	--   singular = true if value is 1 or -1 (to use singular form of units) 	--   clean    = cleaned text with any separators and sign removed 	--              (en digits and '.' decimal mark) 	--   show     = text formatted for output, possibly with ref strip markers 	--              (digits in local language and custom decimal mark) 	-- The resulting show: 	-- * Is for an input value and is spelled if wanted and possible. 	-- * Has a rounded value, if wanted. 	-- * Has digits grouped where necessary, if wanted. 	-- * If negative, a Unicode minus is used; otherwise the sign is 	--   '+' (if the input text used '+'), or is  (if no sign in input). 	text = strip(text or ) 	local reference 	local pos = text:find('\127', 1, true) 	if pos then 		local before = text:sub(1, pos - 1) 		local remainder = text:sub(pos) 		local refs = {} 		while #remainder > 0 do 			local ref, spaces 			ref, spaces, remainder = remainder:match('^(\127[^\127]*UNIQ[^\127]*%-ref[^\127]*\127)(%s*)(.*)') 			if ref then 				table.insert(refs, ref) 			else 				refs = {} 				break 			end 		end 		if #refs > 0 then 			text = strip(before) 			reference = table.concat(refs) 		end 	end 	local clean = to_en(text, parms) 	if clean ==  then 		return false, { another and 'cvt_no_num2' or 'cvt_no_num' } 	end 	local isnegative, propersign = false,   -- most common case 	local singular, show, denominator 	local value = tonumber(clean) 	local altvalue 	if value then 		local sign = clean:sub(1, 1) 		if sign == '+' or sign == '-' then 			propersign = (sign == '+') and '+' or MINUS 			clean = clean:sub(2) 		end 		if value < 0 then 			isnegative = true 			value = -value 		end 	else 		local valstr 		for _, prefix in ipairs({ '-', MINUS, '−' }) do 			-- Including '-' sets isnegative in case input is a fraction like '-2-3/4'. 			local plen = #prefix 			if clean:sub(1, plen) == prefix then 				valstr = clean:sub(plen + 1) 				if valstr:match('^%s') then  -- "- 1" is invalid but "-1 - 1/2" is ok 					return false, { 'cvt_bad_num', text } 				end 				break 			end 		end 		if valstr then 			isnegative = true 			propersign = MINUS 			clean = valstr 			value = tonumber(clean) 		end 		if value == nil then 			if not no_fraction then 				value, altvalue, show, denominator = extract_fraction(parms, clean, isnegative) 			end 			if value == nil then 				return false, { 'cvt_bad_num', text } 			end 			if value <= 1 then 				singular = true  -- for example, "½ mile" or "one half mile" (singular unit) 			end 		end 	end 	if not valid_number(value) then  -- for example, "1e310" may overflow 		return false, { 'cvt_invalid_num' } 	end 	if show == nil then 		-- clean is a non-empty string with no spaces, and does not represent a fraction, 		-- and value = tonumber(clean) is a number >= 0. 		-- If the input uses e-notation, show will be displayed using a power of ten, but 		-- we use the number as given so it might not be normalized scientific notation. 		-- The input value is spelled if specified so any e-notation is ignored; 		-- that allows input like 2e6 to be spelled as "two million" which works 		-- because the spell module converts '2e6' to '2000000' before spelling. 		local function rounded(value, default, exponent) 			local precision = parms.opt_ri 			if precision then 				local fmt = '%.' .. format('%d', precision) .. 'f' 				local result = fmt:format(tonumber(value) + 2e-14)  -- fudge for some common cases of bad rounding 				if not exponent then 					singular = (tonumber(result) == 1) 				end 				return result 			end 			return default 		end 		singular = (value == 1) 		local scientific 		local significand, exponent = clean:match('^([%d.]+)[Ee]([+%-]?%d+)') 		if significand then 			show = with_exponent(parms, rounded(significand, significand, exponent), exponent) 			scientific = true 		else 			show = with_separator(parms, rounded(value, clean)) 		end 		show = propersign .. show 		if parms.opt_spell_in then 			show = spell_number(parms, 'in', propersign .. rounded(value, clean)) or show 			scientific = false 		end 		if scientific then 			parms.opt_scientific = true 		end 	end 	if isnegative and (value ~= 0) then 		value = -value 		altvalue = -(altvalue or value) 	end 	return true, { 		value = value, 		altvalue = altvalue or value, 		singular = singular, 		clean = clean, 		show = show .. (reference or ), 		denominator = denominator, 	} end  local function get_number(text) 	-- Return v, f where: 	--   v = nil (text is not a number) 	-- or 	--   v = value of text (text is a number) 	--   f = true if value is an integer 	-- Input can use en digits or digits in local language, 	-- but no separators, no Unicode minus, and no fraction. 	if text then 		local number = tonumber(to_en(text)) 		if number then 			local _, fracpart = math.modf(number) 			return number, (fracpart == 0) 		end 	end end  local function gcd(a, b) 	-- Return the greatest common denominator for the given values, 	-- which are known to be positive integers. 	if a > b then 		a, b = b, a 	end 	if a <= 0 then 		return b 	end 	local r = b % a 	if r <= 0 then 		return a 	end 	if r == 1 then 		return 1 	end 	return gcd(r, a) end  local function fraction_table(value, denominator) 	-- Return value as a string or a table: 	-- * If result is a string, there is no fraction, and the result 	--   is value formatted as a string of en digits. 	-- * If result is a table, it represents a fraction with named fields: 	--   wholestr, numstr, denstr (strings of en digits for integer, numerator, denominator). 	-- The result is rounded to the nearest multiple of (1/denominator). 	-- If the multiple is zero, no fraction is included. 	-- No fraction is included if value is very large as the fraction would 	-- be unhelpful, particularly if scientific notation is required. 	-- Input value is a non-negative number. 	-- Input denominator is a positive integer for the desired fraction. 	if value <= 0 then 		return '0' 	end 	if denominator <= 0 or value > 1e8 then 		return format('%.2f', value) 	end 	local integer, decimals = math.modf(value) 	local numerator = floor((decimals * denominator) + 		0.5 + 2e-14)  -- add fudge for some common cases of bad rounding 	if numerator >= denominator then 		integer = integer + 1 		numerator = 0 	end 	local wholestr = tostring(integer) 	if numerator > 0 then 		local div = gcd(numerator, denominator) 		if div > 1 then 			numerator = numerator / div 			denominator = denominator / div 		end 		return { 			wholestr = (integer > 0) and wholestr or , 			numstr = tostring(numerator), 			denstr = tostring(denominator), 			value = value, 		} 	end 	return wholestr end  local function preunits(count, preunit1, preunit2) 	-- If count is 1: 	--     ignore preunit2 	--     return p1 	-- else: 	--     preunit1 is used for preunit2 if the latter is empty 	--     return p1, p2 	-- where: 	--     p1 is text to insert before the input unit 	--     p2 is text to insert before the output unit 	--     p1 or p2 may be nil to mean "no preunit" 	-- Using '+' gives output like "5+ feet" (no space before, but space after). 	local function withspace(text, wantboth) 		-- Return text with space before and, if wantboth, after. 		-- However, no space is added if there is a space or ' ' or '-' 		-- at that position ('-' is for adjectival text). 		-- There is also no space if text starts with '&' 		-- (e.g. '°' would display a degree symbol with no preceding space). 		local char = text:sub(1, 1) 		if char == '&' then 			return text  -- an html entity can be used to specify the exact display 		end 		if not (char == ' ' or char == '-' or char == '+') then 			text = ' ' .. text 		end 		if wantboth then 			char = text:sub(-1, -1) 			if not (char == ' ' or char == '-' or text:sub(-6, -1) == ' ') then 				text = text .. ' ' 			end 		end 		return text 	end 	local PLUS = '+ ' 	preunit1 = preunit1 or  	local trim1 = strip(preunit1) 	if count == 1 then 		if trim1 ==  then 			return nil 		end 		if trim1 == '+' then 			return PLUS 		end 		return withspace(preunit1, true) 	end 	preunit1 = withspace(preunit1) 	preunit2 = preunit2 or  	local trim2 = strip(preunit2) 	if trim1 == '+' then 		if trim2 ==  or trim2 == '+' then 			return PLUS, PLUS 		end 		preunit1 = PLUS 	end 	if trim2 ==  then 		if trim1 ==  then 			return nil, nil 		end 		preunit2 = preunit1 	elseif trim2 == '+' then 		preunit2 = PLUS 	elseif trim2 == ' ' then  -- trick to make preunit2 empty 		preunit2 = nil 	else 		preunit2 = withspace(preunit2) 	end 	return preunit1, preunit2 end  local function range_text(range, want_name, parms, before, after, inout) 	-- Return before .. rtext .. after 	-- where rtext is the text that separates two values in a range. 	local rtext, adj_text, exception 	if type(range) == 'table' then 		-- Table must specify range text for ('off' and 'on') or ('input' and 'output'), 		-- and may specify range text for 'adj=on', 		-- and may specify exception = true. 		rtext = range[want_name and 'off' or 'on'] or 				range[((inout == 'in') == (parms.opt_flip == true)) and 'output' or 'input'] 		adj_text = range['adj'] 		exception = range['exception'] 	else 		rtext = range 	end 	if parms.opt_adjectival then 		if want_name or (exception and parms.abbr_org == 'on') then 			rtext = adj_text or rtext:gsub(' ', '-'):gsub(' ', '-') 		end 	end 	if rtext == '–' and after:sub(1, #MINUS) == MINUS then 		rtext = ' – ' 	end 	return before .. rtext .. after end  local function get_composite(parms, iparm, in_unit_table) 	-- Look for a composite input unit. For example,  	-- would result in a call to this function with 	--   iparm = 3 (parms[iparm] = "2", just after the first unit) 	--   in_unit_table = (unit table for "yd"; contains value 1 for number of yards) 	-- Return true, iparm, unit where 	--   iparm = index just after the composite units (7 in above example) 	--   unit = composite unit table holding all input units, 	-- or return true if no composite unit is present in parms, 	-- or return false, t where t is an error message table. 	local default, subinfo 	local composite_units, count = { in_unit_table }, 1 	local fixups = {} 	local total = in_unit_table.valinfo[1].value 	local subunit = in_unit_table 	while subunit.subdivs do  -- subdivs is nil or a table of allowed subdivisions 		local subcode = strip(parms[iparm+1]) 		local subdiv = subunit.subdivs[subcode] or subunit.subdivs[(all_units[subcode] or {}).target] 		if not subdiv then 			break 		end 		local success 		success, subunit = lookup(parms, subcode, 'no_combination') 		if not success then return false, subunit end  -- should never occur 		success, subinfo = extract_number(parms, parms[iparm]) 		if not success then return false, subinfo end 		iparm = iparm + 2 		subunit.inout = 'in' 		subunit.valinfo = { subinfo } 		-- Recalculate total as a number of subdivisions. 		-- subdiv[1] = number of subdivisions per previous unit (integer > 1). 		total = total * subdiv[1] + subinfo.value 		if not default then  -- set by the first subdiv with a default defined 			default = subdiv.default 		end 		count = count + 1 		composite_units[count] = subunit 		if subdiv.unit or subdiv.name then 			fixups[count] = { unit = subdiv.unit, name = subdiv.name, valinfo = subunit.valinfo } 		end 	end 	if count == 1 then 		return true  -- no error and no composite unit 	end 	for i, fixup in pairs(fixups) do 		local unit = fixup.unit 		local name = fixup.name 		if not unit or (count > 2 and name) then 			composite_units[i].fixed_name = name 		else 			local success, alternate = lookup(parms, unit, 'no_combination') 			if not success then return false, alternate end  -- should never occur 			alternate.inout = 'in' 			alternate.valinfo = fixup.valinfo 			composite_units[i] = alternate 		end 	end 	return true, iparm, { 		utype = in_unit_table.utype, 		scale = subunit.scale,  -- scale of last (least significant) unit 		valinfo = { { value = total, clean = subinfo.clean, denominator = subinfo.denominator } }, 		composite = composite_units, 		default = default or in_unit_table.default 	} end  local function translate_parms(parms, kv_pairs) 	-- Update fields in parms by translating each key:value in kv_pairs to terms 	-- used by this module (may involve translating from local language to English). 	-- Also, checks are performed which may display warnings, if enabled. 	-- Return true if successful or return false, t where t is an error message table. 	currency_text = nil  -- local testing can hold module in memory; must clear globals 	local accept_any_text = { 		input = true, 		qid = true, 		qual = true, 		stylein = true, 		styleout = true, 		tracking = true, 	} 	if kv_pairs.adj and kv_pairs.sing then 		-- For enwiki (before translation), warn if attempt to use adj and sing 		-- as the latter is a deprecated alias for the former. 		if kv_pairs.adj ~= kv_pairs.sing and kv_pairs.sing ~=  then 			add_warning(parms, 1, 'cvt_unknown_option', 'sing=' .. kv_pairs.sing) 		end 		kv_pairs.sing = nil 	end 	kv_pairs.comma = kv_pairs.comma or config.comma  -- for plwiki who want default comma=5 	for loc_name, loc_value in pairs(kv_pairs) do 		local en_name = text_code.en_option_name[loc_name] 		if en_name then 			local en_value 			if en_name == '$' or en_name == 'frac' or en_name == 'sigfig' then 				if loc_value ==  then 					add_warning(parms, 2, 'cvt_empty_option', loc_name) 				elseif en_name == '$' then 					-- Value should be a single character like "€" for the euro currency symbol, but anything is accepted. 					currency_text = (loc_value == 'euro') and '€' or loc_value 				else 					local minimum 					local number, is_integer = get_number(loc_value) 					if en_name == 'frac' then 						minimum = 2 						if number and number < 0 then 							parms.opt_fraction_horizontal = true 							number = -number 						end 					else 						minimum = 1 					end 					if number and is_integer and number >= minimum then 						en_value = number 					else 						add_warning(parms, 1, (en_name == 'frac' and 'cvt_bad_frac' or 'cvt_bad_sigfig'), loc_name .. '=' .. loc_value) 					end 				end 			elseif accept_any_text[en_name] then 				en_value = loc_value ~=  and loc_value or nil  -- accept non-empty user text with no validation 				if en_name == 'input' then 					-- May have something like  (empty input) if source is an infobox 					-- with optional fields. In that case, want to output nothing rather than an error. 					parms.input_text = loc_value  -- keep input because parms.input is nil if loc_value == 				end 			else 				en_value = text_code.en_option_value[en_name][loc_value] 				if en_value and en_value:sub(-1) == '?' then 					en_value = en_value:sub(1, -2) 					add_warning(parms, -1, 'cvt_deprecated', loc_name .. '=' .. loc_value) 				end 				if en_value == nil then 					if loc_value ==  then 						add_warning(parms, 2, 'cvt_empty_option', loc_name) 					else 						add_warning(parms, 1, 'cvt_unknown_option', loc_name .. '=' .. loc_value) 					end 				elseif en_value ==  then 					en_value = nil  -- an ignored option like adj=off 				elseif type(en_value) == 'string' and en_value:sub(1, 4) == 'opt_' then 					for _, v in ipairs(split(en_value, ',')) do 						local lhs, rhs = v:match('^(.-)=(.+)$') 						if rhs then 							parms[lhs] = tonumber(rhs) or rhs 						else 							parms[v] = true 						end 					end 					en_value = nil 				end 			end 			parms[en_name] = en_value 		else 			add_warning(parms, 1, 'cvt_unknown_option', loc_name .. '=' .. loc_value) 		end 	end 	local abbr_entered = parms.abbr 	local cfg_abbr = config.abbr 	if cfg_abbr then 		-- Don't warn if invalid because every convert would show that warning. 		if cfg_abbr == 'on always' then 			parms.abbr = 'on' 		elseif cfg_abbr == 'off always' then 			parms.abbr = 'off' 		elseif parms.abbr == nil then 			if cfg_abbr == 'on default' then 				parms.abbr = 'on' 			elseif cfg_abbr == 'off default' then 				parms.abbr = 'off' 			end 		end 	end 	if parms.abbr then 		if parms.abbr == 'unit' then 			parms.abbr = 'on' 			parms.number_word = true 		end 		parms.abbr_org = parms.abbr  -- original abbr, before any flip 	elseif parms.opt_hand_hh then 		parms.abbr_org = 'on' 		parms.abbr = 'on' 	else 		parms.abbr = 'out'  -- default is to abbreviate output only (use symbol, not name) 	end 	if parms.opt_order_out then 		-- Disable options that do not work in a useful way with order=out. 		parms.opt_flip = nil  -- override adj=flip 		parms.opt_spell_in = nil 		parms.opt_spell_out = nil 		parms.opt_spell_upper = nil 	end 	if parms.opt_spell_out and not abbr_entered then 		parms.abbr = 'off'  -- should show unit name when spelling the output value 	end 	if parms.opt_flip then 		local function swap_in_out(option) 			local value = parms[option] 			if value == 'in' then 				parms[option] = 'out' 			elseif value == 'out' then 				parms[option] = 'in' 			end 		end 		swap_in_out('abbr') 		swap_in_out('lk') 		if parms.opt_spell_in and not parms.opt_spell_out then 			-- For simplicity, and because it does not appear to be needed, 			-- user cannot set an option to spell the output only. 			parms.opt_spell_in = nil 			parms.opt_spell_out = true 		end 	end 	if parms.opt_spell_upper then 		parms.spell_upper = parms.opt_flip and 'out' or 'in' 	end 	if parms.opt_table or parms.opt_tablecen then 		if abbr_entered == nil and parms.lk == nil then 			parms.opt_values = true 		end 		parms.table_align = parms.opt_table and 'right' or 'center' 	end 	if parms.table_align or parms.opt_sortable_on then 		parms.need_table_or_sort = true 	end 	local disp_joins = text_code.disp_joins 	local default_joins = disp_joins['b'] 	parms.join_between = default_joins[3] or '; ' 	local disp = parms.disp 	if disp == nil then  -- special case for the most common setting 		parms.joins = default_joins 	elseif disp == 'x' then 		-- Later, parms.joins is set from the input parameters. 	else 		-- Old template does this. 		local abbr = parms.abbr 		if disp == 'slash' then 			if abbr_entered == nil then 				disp = 'slash-nbsp' 			elseif abbr == 'in' or abbr == 'out' then 				disp = 'slash-sp' 			else 				disp = 'slash-nosp' 			end 		elseif disp == 'sqbr' then 			if abbr == 'on' then 				disp = 'sqbr-nbsp' 			else 				disp = 'sqbr-sp' 			end 		end 		parms.joins = disp_joins[disp] or default_joins 		parms.join_between = parms.joins[3] or parms.join_between 		parms.wantname = parms.joins.wantname 	end 	if (en_default and not parms.opt_lang_local and (parms[1] or ):find('%d')) or parms.opt_lang_en then 		from_en_table = nil 	end 	if en_default and from_en_table then 		-- For hiwiki: localized symbol/name is defined with the US symbol/name field, 		-- and is used if output uses localized numbers. 		parms.opt_sp_us = true 	end 	return true end  local function get_values(parms) 	-- If successful, update parms and return true, v, i where 	--   v = table of input values 	--   i = index to next entry in parms after those processed here 	-- or return false, t where t is an error message table. 	local valinfo = collection()  -- numbered table of input values 	local range = collection()  -- numbered table of range items (having, for example, 2 range items requires 3 input values) 	local had_nocomma  -- true if removed "nocomma" kludge from second parameter (like "tonocomma") 	local parm2 = strip(parms[2]) 	if parm2 and parm2:sub(-7, -1) == 'nocomma' then 		parms[2] = strip(parm2:sub(1, -8)) 		parms.opt_nocomma = true 		had_nocomma = true 	end 	local function extractor(i) 		-- If the parameter is not a value, try unpacking it as a range ("1-23" for "1 to 23"). 		-- However, "-1-2/3" is a negative fraction (-1⅔), so it must be extracted first. 		-- Do not unpack a parameter if it is like "3-1/2" which is sometimes incorrectly 		-- used instead of "3+1/2" (and which should not be interpreted as "3 to ½"). 		-- Unpacked items are inserted into the parms table. 		-- The tail recursion allows combinations like "1x2 to 3x4". 		local valstr = strip(parms[i])  -- trim so any '-' as a negative sign will be at start 		local success, result = extract_number(parms, valstr, i > 1) 		if not success and valstr and i < 20 then  -- check i to limit abuse 			local lhs, sep, rhs = valstr:match('^(%S+)%s+(%S+)%s+(%S.*)') 			if lhs and not (sep == '-' and rhs:match('/')) then 				if sep:find('%d') then 					return success, result  -- to reject  with a decent message (en only) 				end 				parms[i] = rhs 				table.insert(parms, i, sep) 				table.insert(parms, i, lhs) 				return extractor(i) 			end 			if not valstr:match('%-.*/') then 				for _, sep in ipairs(text_code.ranges.words) do 					local start, stop = valstr:find(sep, 2, true)  -- start at 2 to skip any negative sign for range '-' 					if start then 						parms[i] = valstr:sub(stop + 1) 						table.insert(parms, i, sep) 						table.insert(parms, i, valstr:sub(1, start - 1)) 						return extractor(i) 					end 				end 			end 		end 		return success, result 	end 	local i = 1 	local is_change 	while true do 		local success, info = extractor(i)  -- need to set parms.opt_nocomma before calling this 		if not success then return false, info end 		i = i + 1 		if is_change then 			info.is_change = true  -- value is after "±" and so is a change (significant for range like ) 			is_change = nil 		end 		valinfo:add(info) 		local range_item = get_range(strip(parms[i])) 		if not range_item then 			break 		end 		i = i + 1 		range:add(range_item) 		if type(range_item) == 'table' then 			-- For range "x", if append unit to some values, append it to all. 			parms.in_range_x = parms.in_range_x or range_item.in_range_x 			parms.out_range_x = parms.out_range_x or range_item.out_range_x 			parms.abbr_range_x = parms.abbr_range_x or range_item.abbr_range_x 			is_change = range_item.is_range_change 		end 	end 	if range.n > 0 then 		if range.n > 30 then  -- limit abuse, although 4 is a more likely upper limit 			return false, { 'cvt_invalid_num' }  -- misleading message but it will do 		end 		parms.range = range 	elseif had_nocomma then 		return false, { 'cvt_unknown', parm2 } 	end 	return true, valinfo, i end  local function simple_get_values(parms) 	-- If input is like "", 	-- return true, i, in_unit, in_unit_table 	-- i = index in parms of what follows valid_unit, if anything. 	-- The valid_value is not negative and does not use a fraction, and 	-- no options requiring further processing of the input are used. 	-- Otherwise, return nothing or return false, parm1 for caller to interpret. 	-- Testing shows this function is successful for 96% of converts in articles, 	-- and that on average it speeds up converts by 8%. 	local clean = to_en(strip(parms[1] or ), parms) 	if parms.opt_ri or parms.opt_spell_in or #clean > 10 or not clean:match('^[0-9.]+$') then 		return false, clean 	end 	local value = tonumber(clean) 	if not value then return end 	local info = { 		value = value, 		altvalue = value, 		singular = (value == 1), 		clean = clean, 		show = with_separator(parms, clean), 	} 	local in_unit = strip(parms[2]) 	local success, in_unit_table = lookup(parms, in_unit, 'no_combination') 	if not success then return end 	in_unit_table.valinfo = { info } 	return true, 3, in_unit, in_unit_table end  local function wikidata_call(parms, operation, ...) 	-- Return true, s where s is the result of a Wikidata operation, 	-- or return false, t where t is an error message table. 	local function worker(...) 		wikidata_code = wikidata_code or require(wikidata_module) 		wikidata_data = wikidata_data or mw.loadData(wikidata_data_module) 		return wikidata_code[operation](wikidata_data, ...) 	end 	local success, status, result = pcall(worker, ...) 	if success then 		return status, result 	end 	if parms.opt_sortable_debug then 		-- Use debug=yes to crash if an error while accessing Wikidata. 		error('Error accessing Wikidata: ' .. status, 0) 	end 	return false, { 'cvt_wd_fail' } end  local function get_parms(parms, args) 	-- If successful, update parms and return true, unit where 	--   parms is a table of all arguments passed to the template 	--        converted to named arguments, and 	--   unit is the input unit table; 	-- or return false, t where t is an error message table. 	-- For special processing (not a convert), can also return 	-- true, wikitext where wikitext is the final result. 	-- The returned input unit table may be for a fake unit using the specified 	-- unit code as the symbol and name, and with bad_mcode = message code table. 	-- MediaWiki removes leading and trailing whitespace from the values of 	-- named arguments. However, the values of numbered arguments include any 	-- whitespace entered in the template, and whitespace is used by some 	-- parameters (example: the numbered parameters associated with "disp=x"). 	local kv_pairs = {}  -- table of input key:value pairs where key is a name; needed because cannot iterate parms and add new fields to it 	for k, v in pairs(args) do 		if type(k) == 'number' or k == 'test' then  -- parameter "test" is reserved for testing and is not translated 			parms[k] = v 		else 			kv_pairs[k] = v 		end 	end 	if parms.test == 'wikidata' then 		local ulookup = function (ucode) 			-- Use empty table for parms so it does not accumulate results when used repeatedly. 			return lookup({}, ucode, 'no_combination') 		end 		return wikidata_call(parms, '_listunits', ulookup) 	end 	local success, msg = translate_parms(parms, kv_pairs) 	if not success then return false, msg end 	if parms.input then 		success, msg = wikidata_call(parms, '_adjustparameters', parms, 1) 		if not success then return false, msg end 	end 	local success, i, in_unit, in_unit_table = simple_get_values(parms) 	if not success then 		if type(i) == 'string' and i:match('^NNN+$') then 			-- Some infoboxes have examples like  (3 or more "N"). 			-- Output an empty string for these. 			return false, { 'cvt_no_output' } 		end 		local valinfo 		success, valinfo, i = get_values(parms) 		if not success then return false, valinfo end 		in_unit = strip(parms[i]) 		i = i + 1 		success, in_unit_table = lookup(parms, in_unit, 'no_combination') 		if not success then 			in_unit = in_unit or  			if parms.opt_ignore_error then  -- display given unit code with no error (for use with ) 				in_unit_table =   -- suppress error message and prevent processing of output unit 			end 			in_unit_table = setmetatable({ 				symbol = in_unit, name2 = in_unit, utype = in_unit, 				scale = 1, default = , defkey = , linkey = , 				bad_mcode = in_unit_table }, unit_mt) 		end 		in_unit_table.valinfo = valinfo 	end 	if parms.test == 'msg' then 		-- Am testing the messages produced when no output unit is specified, and 		-- the input unit has a missing or invalid default. 		-- Set two units for testing that. 		-- LATER: Remove this code. 		if in_unit == 'chain' then 			in_unit_table.default = nil  -- no default 		elseif in_unit == 'rd' then 			in_unit_table.default  = "ft!X!m"  -- an invalid expression 		end 	end 	in_unit_table.inout = 'in'  -- this is an input unit 	if not parms.range then 		local success, inext, composite_unit = get_composite(parms, i, in_unit_table) 		if not success then return false, inext end 		if composite_unit then 			in_unit_table = composite_unit 			i = inext 		end 	end 	if in_unit_table.builtin == 'mach' then 		-- As with old template, a number following Mach as the input unit is the altitude, 		-- and there is no way to specify an altitude for the output unit. 		-- Could put more code in this function to get any output unit and check for 		-- an altitude following that unit. 		local success, info = extract_number(parms, parms[i], false, true) 		if success then 			i = i + 1 			in_unit_table.altitude = info.value 		end 	end 	local word = strip(parms[i]) 	i = i + 1 	local precision, is_bad_precision 	local function set_precision(text) 		local number, is_integer = get_number(text) 		if number then 			if is_integer then 				precision = number 			else 				precision = text 				is_bad_precision = true 			end 			return true  -- text was used for precision, good or bad 		end 	end 	if word and not set_precision(word) then 		parms.out_unit = parms.out_unit or word 		if set_precision(strip(parms[i])) then 			i = i + 1 		end 	end 	if parms.opt_adj_mid then 		word = parms[i] 		i = i + 1 		if word then  -- mid-text words 			if word:sub(1, 1) == '-' then 				parms.mid = word 			else 				parms.mid = ' ' .. word 			end 		end 	end 	if parms.opt_one_preunit then 		parms[parms.opt_flip and 'preunit2' or 'preunit1'] = preunits(1, parms[i]) 		i = i + 1 	end 	if parms.disp == 'x' then 		-- Following is reasonably compatible with the old template. 		local first = parms[i] or 		local second = parms[i+1] or  		i = i + 2 		if strip(first) ==  then  -- user can enter ' ' rather than ' ' to avoid the default 			first = ' [ ' .. first 			second = ' ]' .. second 		end 		parms.joins = { first, second } 	elseif parms.opt_two_preunits then 		local p1, p2 = preunits(2, parms[i], parms[i+1]) 		i = i + 2 		if parms.preunit1 then 			-- To simplify documentation, allow unlikely use of adj=pre with disp=preunit 			-- (however, an output unit must be specified with adj=pre and with disp=preunit). 			parms.preunit1 = parms.preunit1 .. p1 			parms.preunit2 = p2 		else 			parms.preunit1, parms.preunit2 = p1, p2 		end 	end 	if precision == nil then 		if set_precision(strip(parms[i])) then 			i = i + 1 		end 	end 	if is_bad_precision then 		add_warning(parms, 1, 'cvt_bad_prec', precision) 	else 		parms.precision = precision 	end 	for j = i, i + 3 do 		local parm = parms[j]  -- warn if find a non-empty extraneous parameter 		if parm and parm:match('%S') then 			add_warning(parms, 1, 'cvt_unknown_option', parm) 			break 		end 	end 	return true, in_unit_table end  local function record_default_precision(parms, out_current, precision) 	-- If necessary, adjust parameters and return a possibly adjusted precision. 	-- When converting a range of values where a default precision is required, 	-- that default is calculated for each value because the result sometimes 	-- depends on the precise input and output values. This function may cause 	-- the entire convert process to be repeated in order to ensure that the 	-- same default precision is used for each individual convert. 	-- If that were not done, a range like 1000 to 1000.4 may give poor results 	-- because the first output could be heavily rounded, while the second is not. 	-- For range 1000.4 to 1000, this function can give the second convert the 	-- same default precision that was used for the first. 	if not parms.opt_round_each then 		local maxdef = out_current.max_default_precision 		if maxdef then 			if maxdef < precision then 				parms.do_convert_again = true 				out_current.max_default_precision = precision 			else 				precision = out_current.max_default_precision 			end 		else 			out_current.max_default_precision = precision 		end 	end 	return precision end  local function default_precision(parms, invalue, inclean, denominator, outvalue, in_current, out_current, extra) 	-- Return a default value for precision (an integer like 2, 0, -2). 	-- If denominator is not nil, it is the value of the denominator in inclean. 	-- Code follows procedures used in old template. 	local fudge = 1e-14  --  adds this, so we do too 	local prec, minprec, adjust 	local subunit_ignore_trailing_zero 	local subunit_more_precision  -- kludge for "in" used in input like "|2|ft|6|in" 	local composite = in_current.composite 	if composite then 		subunit_ignore_trailing_zero = true  -- input "|2|st|10|lb" has precision 0, not -1 		if composite[#composite].exception == 'subunit_more_precision' then 			subunit_more_precision = true  -- do not use standard precision with input like "|2|ft|6|in" 		end 	end 	if denominator and denominator > 0 then 		prec = math.max(log10(denominator), 1) 	else 		-- Count digits after decimal mark, handling cases like '12.345e6'. 		local exponent 		local integer, dot, decimals, expstr = inclean:match('^(%d*)(%.?)(%d*)(.*)') 		local e = expstr:sub(1, 1) 		if e == 'e' or e == 'E' then 			exponent = tonumber(expstr:sub(2)) 		end 		if dot ==  then 			prec = subunit_ignore_trailing_zero and 0 or -integer:match('0*$'):len() 		else 			prec = #decimals 		end 		if exponent then 			-- So '1230' and '1.23e3' both give prec = -1, and '0.00123' and '1.23e-3' give 5. 			prec = prec - exponent 		end 	end 	if in_current.istemperature and out_current.istemperature then 		-- Converting between common temperatures (°C, °F, °R, K); not keVT. 		-- Kelvin value can be almost zero, or small but negative due to precision problems. 		-- Also, an input value like -300 C (below absolute zero) gives negative kelvins. 		-- Calculate minimum precision from absolute value. 		adjust = 0 		local kelvin = abs((invalue - in_current.offset) * in_current.scale) 		if kelvin < 1e-8 then  -- assume nonzero due to input or calculation precision problem 			minprec = 2 		else 			minprec = 2 - floor(log10(kelvin) + fudge)  -- 3 sigfigs in kelvin 		end 	else 		if invalue == 0 or outvalue <= 0 then 			-- We are never called with a negative outvalue, but it might be zero. 			-- This is special-cased to avoid calculation exceptions. 			return record_default_precision(parms, out_current, 0) 		end 		if out_current.exception == 'integer_more_precision' and floor(invalue) == invalue then 			-- With certain output units that sometimes give poor results 			-- with default rounding, use more precision when the input 			-- value is equal to an integer. An example of a poor result 			-- is when input 50 gives a smaller output than input 49.5. 			-- Experiment shows this helps, but it does not eliminate all 			-- surprises because it is not clear whether "50" should be 			-- interpreted as "from 45 to 55" or "from 49.5 to 50.5". 			adjust = -log10(in_current.scale) 		elseif subunit_more_precision then 			-- Conversion like "" (where subunit is "in") 			-- has a non-standard adjust value, to give more output precision. 			adjust = log10(out_current.scale) + 2 		else 			adjust = log10(abs(invalue / outvalue)) 		end 		adjust = adjust + log10(2) 		-- Ensure that the output has at least two significant figures. 		minprec = 1 - floor(log10(outvalue) + fudge) 	end 	if extra then 		adjust = extra.adjust or adjust 		minprec = extra.minprec or minprec 	end 	return record_default_precision(parms, out_current, math.max(floor(prec + adjust), minprec)) end  local function convert(parms, invalue, info, in_current, out_current) 	-- Convert given input value from one unit to another. 	-- Return output_value (a number) if a simple convert, or 	-- return f, t where 	--   f = true, t = table of information with results, or 	--   f = false, t = error message table. 	local inscale = in_current.scale 	local outscale = out_current.scale 	if not in_current.iscomplex and not out_current.iscomplex then 		return invalue * (inscale / outscale)  -- minimize overhead for most common case 	end 	if in_current.invert or out_current.invert then 		-- Inverted units, such as inverse length, inverse time, or 		-- fuel efficiency. Built-in units do not have invert set. 		if (in_current.invert or 1) * (out_current.invert or 1) < 0 then 			return 1 / (invalue * inscale * outscale) 		end 		return invalue * (inscale / outscale) 	elseif in_current.offset then 		-- Temperature (there are no built-ins for this type of unit). 		if info.is_change then 			return invalue * (inscale / outscale) 		end 		return (invalue - in_current.offset) * (inscale / outscale) + out_current.offset 	else 		-- Built-in unit. 		local in_builtin = in_current.builtin 		local out_builtin = out_current.builtin 		if in_builtin and out_builtin then 			if in_builtin == out_builtin then 				return invalue 			end 			-- There are no cases (yet) where need to convert from one 			-- built-in unit to another, so this should never occur. 			return false, { 'cvt_bug_convert' } 		end 		if in_builtin == 'mach' or out_builtin == 'mach' then 			local adjust 			if in_builtin == 'mach' then 				inscale = speed_of_sound(in_current.altitude) 				adjust = outscale / 0.1 			else 				outscale = speed_of_sound(out_current.altitude) 				adjust = 0.1 / inscale 			end 			return true, { 				outvalue = invalue * (inscale / outscale), 				adjust = log10(adjust) + log10(2), 			} 		elseif in_builtin == 'hand' then 			-- 1 hand = 4 inches; 1.2 hands = 6 inches. 			-- Decimals of a hand are only defined for the first digit, and 			-- the first fractional digit should be a number of inches (1, 2 or 3). 			-- However, this code interprets the entire fractional part as the number 			-- of inches / 10 (so 1.75 inches would be 0.175 hands). 			-- A value like 12.3 hands is exactly 12*4 + 3 inches; base default precision on that. 			local integer, fracpart = math.modf(invalue) 			local inch_value = 4 * integer + 10 * fracpart  -- equivalent number of inches 			local factor = inscale / outscale 			if factor == 4 then 				-- Am converting to inches: show exact result, and use "inches" not "in" by default. 				if parms.abbr_org == nil then 					out_current.usename = true 				end 				local show = format('%g', abs(inch_value))  -- show and clean are unsigned 				if not show:find('e', 1, true) then 					return true, { 						invalue = inch_value, 						outvalue = inch_value, 						clean = show, 						show = show, 					} 				end 			end 			local outvalue = (integer + 2.5 * fracpart) * factor 			local fracstr = info.clean:match('%.(.*)') or 			local fmt 			if fracstr ==  then 				fmt = '%.0f' 			else 				fmt = '%.' .. format('%d', #fracstr - 1) .. 'f' 			end 			return true, { 				invalue = inch_value, 				clean = format(fmt, inch_value), 				outvalue = outvalue, 				minprec = 0, 			} 		end 	end 	return false, { 'cvt_bug_convert' }  -- should never occur end  local function user_style(parms, i) 	-- Return text for a user-specified style for a table cell, or  if none, 	-- given i = 1 (input style) or 2 (output style). 	local style = parms[(i == 1) and 'stylein' or 'styleout'] 	if style then 		style = style:gsub('"', ) 		if style ~=  then 			if style:sub(-1) ~= ';' then 				style = style .. ';' 			end 			return style 		end 	end 	return  end  local function make_table_or_sort(parms, invalue, info, in_current, scaled_top) 	-- Set options to handle output for a table or a sort key, or both. 	-- The text sort key is based on the value resulting from converting 	-- the input to a fake base unit with scale = 1, and other properties 	-- required for a conversion derived from the input unit. 	-- For other modules, return the sort key in a hidden span element, and 	-- the scaled value used to generate the sort key. 	-- If scaled_top is set, it is the scaled value of the numerator of a per unit 	-- to be combined with this unit (the denominator) to make the sort key. 	-- Scaling only works with units that convert with a factor (not temperature). 	local sortkey, scaled_value 	if parms.opt_sortable_on then 		local base = {  -- a fake unit with enough fields for a valid convert 			scale = 1, 			invert = in_current.invert and 1, 			iscomplex = in_current.iscomplex, 			offset = in_current.offset and 0, 		} 		local outvalue, extra = convert(parms, invalue, info, in_current, base) 		if extra then 			outvalue = extra.outvalue 		end 		if in_current.istemperature then 			-- Have converted to kelvin; assume numbers close to zero have a 			-- rounding error and should be zero. 			if abs(outvalue) < 1e-12 then 				outvalue = 0 			end 		end 		if scaled_top and outvalue ~= 0 then 			outvalue = scaled_top / outvalue 		end 		scaled_value = outvalue 		if not valid_number(outvalue) then 			if outvalue < 0 then 				sortkey = '1000000000000000000' 			else 				sortkey = '9000000000000000000' 			end 		elseif outvalue == 0 then 			sortkey = '5000000000000000000' 		else 			local mag = floor(log10(abs(outvalue)) + 1e-14) 			local prefix 			if outvalue > 0 then 				prefix = 7000 + mag 			else 				prefix = 2999 - mag 				outvalue = outvalue + 10^(mag+1) 			end 			sortkey = format('%d', prefix) .. format('%015.0f', floor(outvalue * 10^(14-mag))) 		end 	end 	local sortspan 	if sortkey and not parms.table_align then 		sortspan = parms.opt_sortable_debug and 			'' .. sortkey .. '♠' or 			'' 		parms.join_before = sortspan 	end 	if parms.table_align then 		local sort 		if sortkey then 			sort = ' data-sort-value="' .. sortkey .. '"' 			if parms.opt_sortable_debug then 				parms.join_before = '' .. sortkey .. '' 			end 		else 			sort = 		end 		local style = 'style="text-align:' .. parms.table_align .. ';' 		local joins = {} 		for i = 1, 2 do 			joins[i] = (i == 1 and  or '\n|') .. style .. user_style(parms, i) .. '"' .. sort .. '|' 		end 		parms.table_joins = joins 	end 	return sortspan, scaled_value end  local cvt_to_hand  local function cvtround(parms, info, in_current, out_current) 	-- Return true, t where t is a table with the conversion results; fields: 	--   show = rounded, formatted string with the result of converting value in info, 	--      using the rounding specified in parms. 	--   singular = true if result (after rounding and ignoring any negative sign) 	--      is "1", or like "1.00", or is a fraction with value < 1; 	--   (and more fields shown below, and a calculated 'absvalue' field). 	-- or return false, t where t is an error message table. 	-- Input info.clean uses en digits (it has been translated, if necessary). 	-- Output show uses en or non-en digits as appropriate, or can be spelled. 	if out_current.builtin == 'hand' then 		return cvt_to_hand(parms, info, in_current, out_current) 	end 	local invalue = in_current.builtin == 'hand' and info.altvalue or info.value 	local outvalue, extra = convert(parms, invalue, info, in_current, out_current) 	if parms.need_table_or_sort then 		parms.need_table_or_sort = nil  -- process using first input value only 		make_table_or_sort(parms, invalue, info, in_current) 	end 	if extra then 		if not outvalue then return false, extra end 		invalue = extra.invalue or invalue 		outvalue = extra.outvalue 	end 	if not valid_number(outvalue) then 		return false, { 'cvt_invalid_num' } 	end 	local isnegative 	if outvalue < 0 then 		isnegative = true 		outvalue = -outvalue 	end 	local precision, show, exponent 	local denominator = out_current.frac 	if denominator then 		show = fraction_table(outvalue, denominator) 	else 		precision = parms.precision 		if not precision then 			if parms.sigfig then 				show, exponent = make_sigfig(outvalue, parms.sigfig) 			elseif parms.opt_round then 				local n = parms.opt_round 				if n == 0.5 then 					local integer, fracpart = math.modf(floor(2 * outvalue + 0.5) / 2) 					if fracpart == 0 then 						show = format('%.0f', integer) 					else 						show = format('%.1f', integer + fracpart) 					end 				else 					show = format('%.0f', floor((outvalue / n) + 0.5) * n) 				end 			else 				local inclean = info.clean 				if extra then 					inclean = extra.clean or inclean 					show = extra.show 				end 				if not show then 					precision = default_precision(parms, invalue, inclean, info.denominator, outvalue, in_current, out_current, extra) 				end 			end 		end 	end 	if precision then 		if precision >= 0 then 			local fudge 			if precision <= 8 then 				-- Add a fudge to handle common cases of bad rounding due to inability 				-- to precisely represent some values. This makes the following work: 				--  and . 				-- Old template uses #expr round, which invokes PHP round(). 				-- LATER: Investigate how PHP round() works. 				fudge = 2e-14 			else 				fudge = 0 			end 			local fmt = '%.' .. format('%d', precision) .. 'f' 			local success 			success, show = pcall(format, fmt, outvalue + fudge) 			if not success then 				return false, { 'cvt_big_prec', tostring(precision) } 			end 		else 			precision = -precision  -- #digits to zero (in addition to any digits after dot) 			local shift = 10 ^ precision 			show = format('%.0f', outvalue/shift) 			if show ~= '0' then 				exponent = #show + precision 			end 		end 	end 	local t = format_number(parms, show, exponent, isnegative) 	if type(show) == 'string' then 		-- Set singular using match because on some systems 0.99999999999999999 is 1.0. 		if exponent then 			t.singular = (exponent == 1 and show:match('^10*$')) 		else 			t.singular = (show == '1' or show:match('^1%.0*$')) 		end 	else 		t.fraction_table = show 		t.singular = (outvalue <= 1)  -- cannot have 'fraction == 1', but if it were possible it would be singular 	end 	t.raw_absvalue = outvalue  -- absolute value before rounding 	return true, setmetatable(t, { 		__index = function (self, key) 			if key == 'absvalue' then 				-- Calculate absolute value after rounding, if needed. 				local clean, exponent = rawget(self, 'clean'), rawget(self, 'exponent') 				local value = tonumber(clean)  -- absolute value (any negative sign has been ignored) 				if exponent then 					value = value * 10^exponent 				end 				rawset(self, key, value) 				return value 			end 		end }) end  function cvt_to_hand(parms, info, in_current, out_current) 	-- Convert input to hands, inches. 	-- Return true, t where t is a table with the conversion results; 	-- or return false, t where t is an error message table. 	if parms.abbr_org == nil then 		out_current.usename = true  -- default is to show name not symbol 	end 	local precision = parms.precision 	local frac = out_current.frac 	if not frac and precision and precision > 1 then 		frac = (precision == 2) and 2 or 4 	end 	local out_next = out_current.out_next 	if out_next then 		-- Use magic knowledge to determine whether the next unit is inches without requiring i18n. 		-- The following ensures that when the output combination "hand in" is used, the inches 		-- value is rounded to match the hands value. Also, displaying say "61½" instead of 61.5 		-- is better as 61.5 implies the value is not 61.4. 		if out_next.exception == 'subunit_more_precision' then 			out_next.frac = frac 		end 	end 	-- Convert to inches; calculate hands from that. 	local dummy_unit_table = { scale = out_current.scale / 4, frac = frac } 	local success, outinfo = cvtround(parms, info, in_current, dummy_unit_table) 	if not success then return false, outinfo end 	local tfrac = outinfo.fraction_table 	local inches = outinfo.raw_absvalue 	if tfrac then 		inches = floor(inches)  -- integer part only; fraction added later 	else 		inches = floor(inches + 0.5)  -- a hands measurement never shows decimals of an inch 	end 	local hands, inches = divide(inches, 4) 	outinfo.absvalue = hands + inches/4  -- supposed to be the absolute rounded value, but this is close enough 	local inchstr = tostring(inches)  -- '0', '1', '2' or '3' 	if precision and precision <= 0 then  -- using negative or 0 for precision rounds to nearest hand 		hands = floor(outinfo.raw_absvalue/4 + 0.5) 		inchstr = 	elseif tfrac then 		-- Always show an integer before fraction (like "15.0½") because "15½" means 15-and-a-half hands. 		inchstr = numdot .. format_fraction(parms, 'out', false, inchstr, tfrac.numstr, tfrac.denstr) 	else 		inchstr = numdot .. from_en(inchstr) 	end 	outinfo.show = outinfo.sign .. with_separator(parms, format('%.0f', hands)) .. inchstr 	return true, outinfo end  local function evaluate_condition(value, condition) 	-- Return true or false from applying a conditional expression to value, 	-- or throw an error if invalid. 	-- A very limited set of expressions is supported: 	--    v < 9 	--    v * 9 < 9 	-- where 	--    'v' is replaced with value 	--    9 is any number (as defined by Lua tonumber) 	--      only en digits are accepted 	--    '<' can also be '<=' or '>' or '>=' 	-- In addition, the following form is supported: 	--    LHS and RHS 	-- where 	--    LHS, RHS = any of above expressions. 	local function compare(value, text) 		local arithop, factor, compop, limit = text:match('^%s*v%s*([*]?)(.-)([<>]=?)(.*)$') 		if arithop == nil then 			error('Invalid default expression', 0) 		elseif arithop == '*' then 			factor = tonumber(factor) 			if factor == nil then 				error('Invalid default expression', 0) 			end 			value = value * factor 		end 		limit = tonumber(limit) 		if limit == nil then 			error('Invalid default expression', 0) 		end 		if compop == '<' then 			return value < limit 		elseif compop == '<=' then 			return value <= limit 		elseif compop == '>' then 			return value > limit 		elseif compop == '>=' then 			return value >= limit 		end 		error('Invalid default expression', 0)  -- should not occur 	end 	local lhs, rhs = condition:match('^(.-%W)and(%W.*)') 	if lhs == nil then 		return compare(value, condition) 	end 	return compare(value, lhs) and compare(value, rhs) end  local function get_default(value, unit_table) 	-- Return true, s where s = name of unit's default output unit, 	-- or return false, t where t is an error message table. 	-- Some units have a default that depends on the input value 	-- (the first value if a range of values is used). 	-- If '!' is in the default, the first bang-delimited field is an 	-- expression that uses 'v' to represent the input value. 	-- Example: 'v < 120 ! small ! big ! suffix' (suffix is optional) 	-- evaluates 'v < 120' as a boolean with result 	-- 'smallsuffix' if (value < 120), or 'bigsuffix' otherwise. 	-- Input must use en digits and '.' decimal mark. 	local default = data_code.default_exceptions[unit_table.defkey or unit_table.symbol] or unit_table.default 	if not default then 		local per = unit_table.per 		if per then 			local function a_default(v, u) 				local success, ucode = get_default(v, u) 				if not success then 					return '?'  -- an unlikely error has occurred; will cause lookup of default to fail 				end 				-- Attempt to use only the first unit if a combination or output multiple. 				-- This is not bulletproof but should work for most cases. 				-- Where it does not work, the convert will need to specify the wanted output unit. 				local t = all_units[ucode] 				if t then 					local combo = t.combination 					if combo then 						-- For a multiple like ftin, the "first" unit (ft) is last in the combination. 						local i = t.multiple and table_len(combo) or 1 						ucode = combo[i] 					end 				else 					-- Try for an automatically generated combination. 					local item = ucode:match('^(.-)%+') or ucode:match('^(%S+)%s') 					if all_units[item] then 						return item 					end 				end 				return ucode 			end 			local unit1, unit2 = per[1], per[2] 			local def1 = (unit1 and a_default(value, unit1) or unit_table.vprefix or ) 			local def2 = a_default(1, unit2)  -- 1 because per unit of denominator 			return true, def1 .. '/' .. def2 		end 		return false, { 'cvt_no_default', unit_table.symbol } 	end 	if default:find('!', 1, true) == nil then 		return true, default 	end 	local t = split(default, '!') 	if #t == 3 or #t == 4 then 		local success, result = pcall(evaluate_condition, value, t[1]) 		if success then 			default = result and t[2] or t[3] 			if #t == 4 then 				default = default .. t[4] 			end 			return true, default 		end 	end 	return false, { 'cvt_bad_default', unit_table.symbol } end  local linked_pages  -- to record linked pages so will not link to the same page more than once  local function unlink(unit_table) 	-- Forget that the given unit has previously been linked (if it has). 	-- That is needed when processing a range of inputs or outputs when an id 	-- for the first range value may have been evaluated, but only an id for 	-- the last value is displayed, and that id may need to be linked. 	linked_pages[unit_table.unitcode or unit_table] = nil end  local function make_link(link, id, unit_table) 	-- Return wikilink "id", possibly abbreviated as in examples: 	--   mile  --> mile 	--   miles --> miles 	-- However, just id is returned if: 	-- * no link given (so caller does not need to check if a link was defined); or 	-- * link has previously been used during the current convert (to avoid overlinking). 	local link_key 	if unit_table then 		link_key = unit_table.unitcode or unit_table 	else 		link_key = link 	end 	if not link or link ==  or linked_pages[link_key] then 		return id 	end 	linked_pages[link_key] = true 	-- Following only works for language en, but it should be safe on other wikis, 	-- and overhead of doing it generally does not seem worthwhile. 	local l = link:sub(1, 1):lower() .. link:sub(2) 	if link == id or l == id then 		return '' .. id .. '' 	elseif link .. 's' == id or l .. 's' == id then 		return '' .. id:sub(1, -2) .. 's' 	else 		return '' .. id .. '' 	end end  local function variable_name(clean, unit_table) 	-- For slwiki, a unit name depends on the value. 	-- Parameter clean is the unsigned rounded value in en digits, as a string. 	-- Value             Source    Example for "m" 	-- integer 1:        name1     meter  (also is the name of the unit) 	-- integer 2:        var{1}    metra 	-- integer 3 and 4:  var{2}    metri 	-- integer else:     var{3}    metrov (0 and 5 or more) 	-- real/fraction:    var{4}    metra 	-- var{i} means the i'th field in unit_table.varname if it exists and has 	-- an i'th field, otherwise name2. 	-- Fields are separated with "!" and are not empty. 	-- A field for a unit using an SI prefix has the prefix name inserted, 	-- replacing '#' if found, or before the field otherwise. 	local vname 	if clean == '1' then 		vname = unit_table.name1 	elseif unit_table.varname then 		local i 		if clean == '2' then 			i = 1 		elseif clean == '3' or clean == '4' then 			i = 2 		elseif clean:find('.', 1, true) then 			i = 4 		else 			i = 3 		end 		if i > 1 and varname == 'pl' then 			i = i - 1 		end 		vname = split(unit_table.varname, '!')[i] 	end 	if vname then 		local si_name = rawget(unit_table, 'si_name') or  		local pos = vname:find('#', 1, true) 		if pos then 			vname = vname:sub(1, pos - 1) .. si_name .. vname:sub(pos + 1) 		else 			vname = si_name .. vname 		end 		return vname 	end 	return unit_table.name2 end  local function linked_id(parms, unit_table, key_id, want_link, clean) 	-- Return final unit id (symbol or name), optionally with a wikilink, 	-- and update unit_table.sep if required. 	-- key_id is one of: 'symbol', 'sym_us', 'name1', 'name1_us', 'name2', 'name2_us'. 	local abbr_on = (key_id == 'symbol' or key_id == 'sym_us') 	if abbr_on and want_link then 		local symlink = rawget(unit_table, 'symlink') 		if symlink then 			return symlink  -- for exceptions that have the linked symbol built-in 		end 	end 	local multiplier = rawget(unit_table, 'multiplier') 	local per = unit_table.per 	if per then 		local paren1, paren2 = ,   -- possible parentheses around bottom unit 		local unit1 = per[1]  -- top unit_table, or nil 		local unit2 = per[2]  -- bottom unit_table 		if abbr_on then 			if not unit1 then 				unit_table.sep =   -- no separator in "$2/acre" 			end 			if not want_link then 				local symbol = unit_table.symbol_raw 				if symbol then 					return symbol  -- for exceptions that have the symbol built-in 				end 			end 			if (unit2.symbol):find('⋅', 1, true) then 				paren1, paren2 = '(', ')' 			end 		end 		local key_id2  -- unit2 is always singular 		if key_id == 'name2' then 			key_id2 = 'name1' 		elseif key_id == 'name2_us' then 			key_id2 = 'name1_us' 		else 			key_id2 = key_id 		end 		local result 		if abbr_on then 			result = '/' 		elseif omitsep then 			result = per_word 		elseif unit1 then 			result = ' ' .. per_word .. ' ' 		else 			result = per_word .. ' ' 		end 		if want_link and unit_table.link then 			if abbr_on or not varname then 				result = (unit1 and linked_id(parms, unit1, key_id, false, clean) or ) .. result .. linked_id(parms, unit2, key_id2, false, '1') 			else 				result = (unit1 and variable_name(clean, unit1) or ) .. result .. variable_name('1', unit2) 			end 			if omit_separator(result) then 				unit_table.sep =  			end 			return make_link(unit_table.link, result, unit_table) 		end 		if unit1 then 			result = linked_id(parms, unit1, key_id, want_link, clean) .. result 			if unit1.sep then 				unit_table.sep = unit1.sep 			end 		elseif omitsep then 			unit_table.sep = 		end 		return result .. paren1 .. linked_id(parms, unit2, key_id2, want_link, '1') .. paren2 	end 	if multiplier then 		-- A multiplier (like "100" in "100km") forces the unit to be plural. 		multiplier = from_en(multiplier) 		if not omitsep then 			multiplier = multiplier .. (abbr_on and ' ' or ' ') 		end 		if not abbr_on then 			if key_id == 'name1' then 				key_id = 'name2' 			elseif key_id == 'name1_us' then 				key_id = 'name2_us' 			end 		end 	else 		multiplier =  	end 	local id = unit_table.fixed_name or ((varname and not abbr_on) and variable_name(clean, unit_table) or unit_table[key_id]) 	if omit_separator(id) then 		unit_table.sep = 	end 	if want_link then 		local link = data_code.link_exceptions[unit_table.linkey or unit_table.symbol] or unit_table.link 		if link then 			local before =  			local i = unit_table.customary 			if i == 1 and parms.opt_sp_us then 				i = 2  -- show "U.S." not "US" 			end 			if i == 3 and abbr_on then 				i = 4  -- abbreviate "imperial" to "imp" 			end 			local customary = text_code.customary_units[i] 			if customary then 				-- LATER: This works for language en only, but it's esoteric so ignore for now. 				local pertext 				if id:sub(1, 1) == '/' then 					-- Want unit "/USgal" to display as "/U.S. gal", not "U.S. /gal". 					pertext = '/' 					id = id:sub(2) 				elseif id:sub(1, 4) == 'per ' then 					-- Similarly want "per U.S. gallon", not "U.S. per gallon" (but in practice this is unlikely to be used). 					pertext = 'per ' 					id = id:sub(5) 				else 					pertext = 				end 				-- Omit any "US"/"U.S."/"imp"/"imperial" from start of id since that will be inserted. 				local removes = (i < 3) and { 'US ', 'US ', 'U.S. ', 'U.S. ' } or { 'imp ', 'imp ', 'imperial ' } 				for _, prefix in ipairs(removes) do 					local plen = #prefix 					if id:sub(1, plen) == prefix then 						id = id:sub(plen + 1) 						break 					end 				end 				before = pertext .. make_link(customary.link, customary[1]) .. ' ' 			end 			id = before .. make_link(link, id, unit_table) 		end 	end 	return multiplier .. id end  local function make_id(parms, which, unit_table) 	-- Return id, f where 	--   id = unit name or symbol, possibly modified 	--   f = true if id is a name, or false if id is a symbol 	-- using the value for index 'which', and for 'in' or 'out' (unit_table.inout). 	-- Result is  if no symbol/name is to be used. 	-- In addition, set unit_table.sep = ' ' or ' ' or 	-- (the separator that caller will normally insert before the id). 	if parms.opt_values then 		unit_table.sep =  		return 	end 	local inout = unit_table.inout 	local info = unit_table.valinfo[which] 	local abbr_org = parms.abbr_org 	local adjectival = parms.opt_adjectival 	local lk = parms.lk 	local want_link = (lk == 'on' or lk == inout) 	local usename = unit_table.usename 	local singular = info.singular 	local want_name 	if usename then 		want_name = true 	else 		if abbr_org == nil then 			if parms.wantname then 				want_name = true 			end 			if unit_table.usesymbol then 				want_name = false 			end 		end 		if want_name == nil then 			local abbr = parms.abbr 			if abbr == 'on' or abbr == inout or (abbr == 'mos' and inout == 'out') then 				want_name = false 			else 				want_name = true 			end 		end 	end 	local key 	if want_name then 		if lk == nil and unit_table.builtin == 'hand' then 			want_link = true 		end 		if parms.opt_use_nbsp then 			unit_table.sep = ' ' 		else 			unit_table.sep = ' ' 		end 		if parms.opt_singular then 			local value 			if inout == 'in' then 				value = info.value 			else 				value = info.absvalue 			end 			if value then  -- some unusual units do not always set value field 				value = abs(value) 				singular = (0 < value and value < 1.0001) 			end 		end 		if unit_table.engscale then 			-- engscale: so "|1|e3kg" gives "1 thousand kilograms" (plural) 			singular = false 		end 		key = (adjectival or singular) and 'name1' or 'name2' 		if parms.opt_sp_us then 			key = key .. '_us' 		end 	else 		if unit_table.builtin == 'hand' then 			if parms.opt_hand_hh then 				unit_table.symbol = 'hh'  -- LATER: might want i18n applied to this 			end 		end 		unit_table.sep = ' ' 		key = parms.opt_sp_us and 'sym_us' or 'symbol' 	end 	return linked_id(parms, unit_table, key, want_link, info.clean), want_name end  local function decorate_value(parms, unit_table, which, number_word) 	-- If needed, update unit_table so values will be shown with extra information. 	-- For consistency with the old template (but different from fmtpower), 	-- the style to display powers of 10 includes "display:none" to allow some 	-- browsers to copy, for example, "10³" as "10^3", rather than as "103". 	local info 	local engscale = unit_table.engscale 	local prefix = unit_table.vprefix 	if engscale or prefix then 		info = unit_table.valinfo[which] 		if info.decorated then 			return  -- do not redecorate if repeating convert 		end 		info.decorated = true 		if engscale then 			local inout = unit_table.inout 			local abbr = parms.abbr 			if (abbr == 'on' or abbr == inout) and not parms.number_word then 				info.show = info.show .. 					'×' .. 					from_en('10') .. 					'^' .. 					from_en(tostring(engscale.exponent)) .. '' 			elseif number_word then 				local number_id 				local lk = parms.lk 				if lk == 'on' or lk == inout then 					number_id = make_link(engscale.link, engscale[1]) 				else 					number_id = engscale[1] 				end 				-- WP:NUMERAL recommends " " in values like "12 million". 				info.show = info.show .. (parms.opt_adjectival and '-' or ' ') .. number_id 			end 		end 		if prefix then 			info.show = prefix .. info.show 		end 	end end  local function process_input(parms, in_current) 	-- Processing required once per conversion. 	-- Return block of text to represent input (value/unit). 	if parms.opt_output_only or parms.opt_output_number_only or parms.opt_output_unit_only then 		parms.joins = { ,  } 		return  	end 	local first_unit 	local composite = in_current.composite  -- nil or table of units 	if composite then 		first_unit = composite[1] 	else 		first_unit = in_current 	end 	local id1, want_name = make_id(parms, 1, first_unit) 	local sep = first_unit.sep  -- separator between value and unit, set by make_id 	local preunit = parms.preunit1 	if preunit then 		sep =   -- any separator is included in preunit 	else 		preunit =  	end 	if parms.opt_input_unit_only then 		parms.joins = { ,  } 		if composite then 			local parts = { id1 } 			for i, unit in ipairs(composite) do 				if i > 1 then 					table.insert(parts, (make_id(parms, 1, unit))) 				end 			end 			id1 = table.concat(parts, ' ') 		end 		if want_name and parms.opt_adjectival then 			return preunit .. hyphenated(id1) 		end 		return  preunit .. id1 	end 	if parms.opt_also_symbol and not composite and not parms.opt_flip then 		local join1 = parms.joins[1] 		if join1 == ' (' or join1 == ' [' then 			parms.joins = { ' [' .. first_unit[parms.opt_sp_us and 'sym_us' or 'symbol'] .. ']' .. join1 , parms.joins[2] } 		end 	end 	if in_current.builtin == 'mach' and first_unit.sep ~=  then  --  means omitsep with non-enwiki name 		local prefix = id1 .. ' ' 		local range = parms.range 		local valinfo = first_unit.valinfo 		local result = prefix .. valinfo[1].show 		if range then 			-- For simplicity and because more not needed, handle one range item only. 			local prefix2 = make_id(parms, 2, first_unit) .. ' ' 			result = range_text(range[1], want_name, parms, result, prefix2 .. valinfo[2].show, 'in') 		end 		return preunit .. result 	end 	if composite then 		-- Simplify: assume there is no range, and no decoration. 		local mid = (not parms.opt_flip) and parms.mid or 		local sep1 = ' ' 		local sep2 = ' ' 		if parms.opt_adjectival and want_name then 			sep1 = '-' 			sep2 = '-' 		end 		if omitsep and sep ==  then 			-- Testing the id of the most significant unit should be sufficient. 			sep1 = 			sep2 =  		end 		local parts = { first_unit.valinfo[1].show .. sep1 .. id1 } 		for i, unit in ipairs(composite) do 			if i > 1 then 				table.insert(parts, unit.valinfo[1].show .. sep1 .. (make_id(parms, 1, unit))) 			end 		end 		return table.concat(parts, sep2) .. mid 	end 	local add_unit = (parms.abbr == 'mos') or 		parms[parms.opt_flip and 'out_range_x' or 'in_range_x'] or 		(not want_name and parms.abbr_range_x) 	local range = parms.range 	if range and not add_unit then 		unlink(first_unit) 	end 	local id = range and make_id(parms, range.n + 1, first_unit) or id1 	local extra, was_hyphenated = hyphenated_maybe(parms, want_name, sep, id, 'in') 	if was_hyphenated then 		add_unit = false 	end 	local result 	local valinfo = first_unit.valinfo 	if range then 		for i = 0, range.n do 			local number_word 			if i == range.n then 				add_unit = false 				number_word = true 			end 			decorate_value(parms, first_unit, i+1, number_word) 			local show = valinfo[i+1].show 			if add_unit then 				show = show .. first_unit.sep .. (i == 0 and id1 or make_id(parms, i+1, first_unit)) 			end 			if i == 0 then 				result = show 			else 				result = range_text(range[i], want_name, parms, result, show, 'in') 			end 		end 	else 		decorate_value(parms, first_unit, 1, true) 		result = valinfo[1].show 	end 	return result .. preunit .. extra end  local function process_one_output(parms, out_current) 	-- Processing required for each output unit. 	-- Return block of text to represent output (value/unit). 	local inout = out_current.inout  -- normally 'out' but can be 'in' for order=out 	local id1, want_name = make_id(parms, 1, out_current) 	local sep = out_current.sep  -- set by make_id 	local preunit = parms.preunit2 	if preunit then 		sep =   -- any separator is included in preunit 	else 		preunit =  	end 	if parms.opt_output_unit_only then 		if want_name and parms.opt_adjectival then 			return preunit .. hyphenated(id1) 		end 		return preunit .. id1 	end 	if out_current.builtin == 'mach' and out_current.sep ~=  then  --  means omitsep with non-enwiki name 		local prefix = id1 .. ' ' 		local range = parms.range 		local valinfo = out_current.valinfo 		local result = prefix .. valinfo[1].show 		if range then 			-- For simplicity and because more not needed, handle one range item only. 			result = range_text(range[1], want_name, parms, result, prefix .. valinfo[2].show, inout) 		end 		return preunit .. result 	end 	local add_unit = (parms[parms.opt_flip and 'in_range_x' or 'out_range_x'] or 		(not want_name and parms.abbr_range_x)) and 		not parms.opt_output_number_only 	local range = parms.range 	if range and not add_unit then 		unlink(out_current) 	end 	local id = range and make_id(parms, range.n + 1, out_current) or id1 	local extra, was_hyphenated = hyphenated_maybe(parms, want_name, sep, id, inout) 	if was_hyphenated then 		add_unit = false 	end 	local result 	local valinfo = out_current.valinfo 	if range then 		for i = 0, range.n do 			local number_word 			if i == range.n then 				add_unit = false 				number_word = true 			end 			decorate_value(parms, out_current, i+1, number_word) 			local show = valinfo[i+1].show 			if add_unit then 				show = show .. out_current.sep .. (i == 0 and id1 or make_id(parms, i+1, out_current)) 			end 			if i == 0 then 				result = show 			else 				result = range_text(range[i], want_name, parms, result, show, inout) 			end 		end 	else 		decorate_value(parms, out_current, 1, true) 		result = valinfo[1].show 	end 	if parms.opt_output_number_only then 		return result 	end 	return result .. preunit .. extra end  local function make_output_single(parms, in_unit_table, out_unit_table) 	-- Return true, item where item = wikitext of the conversion result 	-- for a single output (which is not a combination or a multiple); 	-- or return false, t where t is an error message table. 	if parms.opt_order_out and in_unit_table.unitcode == out_unit_table.unitcode then 		out_unit_table.valinfo = in_unit_table.valinfo 	else 		out_unit_table.valinfo = collection() 		for _, v in ipairs(in_unit_table.valinfo) do 			local success, info = cvtround(parms, v, in_unit_table, out_unit_table) 			if not success then return false, info end 			out_unit_table.valinfo:add(info) 		end 	end 	return true, process_one_output(parms, out_unit_table) end  local function make_output_multiple(parms, in_unit_table, out_unit_table) 	-- Return true, item where item = wikitext of the conversion result 	-- for an output which is a multiple (like 'ftin'); 	-- or return false, t where t is an error message table. 	local inout = out_unit_table.inout  -- normally 'out' but can be 'in' for order=out 	local multiple = out_unit_table.multiple  -- table of scaling factors (will not be nil) 	local combos = out_unit_table.combination  -- table of unit tables (will not be nil) 	local abbr = parms.abbr 	local abbr_org = parms.abbr_org 	local disp = parms.disp 	local want_name = (abbr_org == nil and (disp == 'or' or disp == 'slash')) or 						not (abbr == 'on' or abbr == inout or abbr == 'mos') 	local want_link = (parms.lk == 'on' or parms.lk == inout) 	local mid = parms.opt_flip and parms.mid or 	local sep1 = ' ' 	local sep2 = ' ' 	if parms.opt_adjectival and want_name then 		sep1 = '-' 		sep2 = '-' 	end 	local do_spell = parms.opt_spell_out 	parms.opt_spell_out = nil  -- so the call to cvtround does not spell the value 	local function make_result(info, isfirst) 		local fmt, outvalue, sign 		local results = {} 		for i = 1, #combos do 			local tfrac, thisvalue, strforce 			local out_current = combos[i] 			out_current.inout = inout 			local scale = multiple[i] 			if i == 1 then  -- least significant unit ('in' from 'ftin') 				local decimals 				out_current.frac = out_unit_table.frac 				local success, outinfo = cvtround(parms, info, in_unit_table, out_current) 				if not success then return false, outinfo end 				if isfirst then 					out_unit_table.valinfo = { outinfo }  -- in case output value of first least significant unit is needed 				end 				sign = outinfo.sign 				tfrac = outinfo.fraction_table 				if outinfo.is_scientific then 					strforce = outinfo.show 					decimals =  				elseif tfrac then 					decimals = 				else 					local show = outinfo.show  -- number as a string in local language 					local p1, p2 = show:find(numdot, 1, true) 					decimals = p1 and show:sub(p2 + 1) or   -- text after numdot, if any 				end 				fmt = '%.' .. ulen(decimals) .. 'f'  -- to reproduce precision 				if decimals ==  then 					if tfrac then 						outvalue = floor(outinfo.raw_absvalue)  -- integer part only; fraction added later 					else 						outvalue = floor(outinfo.raw_absvalue + 0.5)  -- keep all integer digits of least significant unit 					end 				else 					outvalue = outinfo.absvalue 				end 			end 			if scale then 				outvalue, thisvalue = divide(outvalue, scale) 			else 				thisvalue = outvalue 			end 			local id 			if want_name then 				if varname then 					local clean 					if strforce or tfrac then 						clean = '.1'  -- dummy value to force name for floating point 					else 						clean = format(fmt, thisvalue) 					end 					id = variable_name(clean, out_current) 				else 					local key = 'name2' 					if parms.opt_adjectival then 						key = 'name1' 					elseif tfrac then 						if thisvalue == 0 then 							key = 'name1' 						end 					elseif parms.opt_singular then 						if 0 < thisvalue and thisvalue < 1.0001 then 							key = 'name1' 						end 					else 						if thisvalue == 1 then 							key = 'name1' 						end 					end 					id = out_current[key] 				end 			else 				id = out_current['symbol'] 			end 			if i == 1 and omit_separator(id) then 				-- Testing the id of the least significant unit should be sufficient. 				sep1 =  				sep2 = 			end 			if want_link then 				local link = out_current.link 				if link then 					id = make_link(link, id, out_current) 				end 			end 			local strval 			local spell_inout = (i == #combos or outvalue == 0) and inout or   -- trick so the last value processed (first displayed) has uppercase, if requested 			if strforce and outvalue == 0 then 				sign =   -- any sign is in strforce 				strval = strforce  -- show small values in scientific notation; will only use least significant unit 			elseif tfrac then 				local wholestr = (thisvalue > 0) and tostring(thisvalue) or nil 				strval = format_fraction(parms, spell_inout, false, wholestr, tfrac.numstr, tfrac.denstr, do_spell) 			else 				strval = (thisvalue == 0) and from_en('0') or with_separator(parms, format(fmt, thisvalue)) 				if do_spell then 					strval = spell_number(parms, spell_inout, strval) or strval 				end 			end 			table.insert(results, strval .. sep1 .. id) 			if outvalue == 0 then 				break 			end 			fmt = '%.0f'  -- only least significant unit can have a non-integral value 		end 		local reversed, count = {}, #results 		for i = 1, count do 			reversed[i] = results[count + 1 - i] 		end 		return true, sign .. table.concat(reversed, sep2) 	end 	local valinfo = in_unit_table.valinfo 	local success, result = make_result(valinfo[1], true) 	if not success then return false, result end 	local range = parms.range 	if range then 		for i = 1, range.n do 			local success, result2 = make_result(valinfo[i+1]) 			if not success then return false, result2 end 			result = range_text(range[i], want_name, parms, result, result2, inout) 		end 	end 	return true, result .. mid end  local function process(parms, in_unit_table, out_unit_table) 	-- Return true, s, outunit where s = final wikitext result, 	-- or return false, t where t is an error message table. 	linked_pages = {} 	local success, bad_output 	local bad_input_mcode = in_unit_table.bad_mcode  -- nil if input unit is a valid convert unit 	local out_unit = parms.out_unit 	if out_unit == nil or out_unit ==  or type(out_unit) == 'function' then 		if bad_input_mcode or parms.opt_input_unit_only then 			bad_output = 		else 			local getdef = type(out_unit) == 'function' and out_unit or get_default 			success, out_unit = getdef(in_unit_table.valinfo[1].value, in_unit_table) 			parms.out_unit = out_unit 			if not success then 				bad_output = out_unit 			end 		end 	end 	if not bad_output and not out_unit_table then 		success, out_unit_table = lookup(parms, out_unit, 'any_combination') 		if success then 			local mismatch = check_mismatch(in_unit_table, out_unit_table) 			if mismatch then 				bad_output = mismatch 			end 		else 			bad_output = out_unit_table 		end 	end 	local lhs, rhs 	local flipped = parms.opt_flip and not bad_input_mcode 	if bad_output then 		rhs = (bad_output == ) and  or message(parms, bad_output) 	elseif parms.opt_input_unit_only then 		rhs =  	else 		local combos  -- nil (for 'ft' or 'ftin'), or table of unit tables (for 'm ft') 		if not out_unit_table.multiple then  -- nil/false ('ft' or 'm ft'), or table of factors ('ftin') 			combos = out_unit_table.combination 		end 		local frac = parms.frac  -- nil or denominator of fraction for output values 		if frac then 			-- Apply fraction to the unit (if only one), or to non-SI units (if a combination), 			-- except that if a precision is also specified, the fraction only applies to 			-- the hand unit; that allows the following result: 			--  → 156 centimetres (61.4 in; 15.1½ hands) 			-- However, the following is handled elsewhere as a special case: 			--  → 156 centimetres (15.1½ hands; 61½ in) 			if combos then 				local precision = parms.precision 				for _, unit in ipairs(combos) do 					if unit.builtin == 'hand' or (not precision and not unit.prefixes) then 						unit.frac = frac 					end 				end 			else 				out_unit_table.frac = frac 			end 		end 		local outputs = {} 		local imax = combos and #combos or 1  -- 1 (single unit) or number of unit tables 		if imax == 1 then 			parms.opt_order_out = nil  -- only useful with an output combination 		end 		if not flipped and not parms.opt_order_out then 			-- Process left side first so any duplicate links (from lk=on) are suppressed 			-- on right. Example:  			lhs = process_input(parms, in_unit_table) 		end 		for i = 1, imax do 			local success, item 			local out_current = combos and combos[i] or out_unit_table 			out_current.inout = 'out' 			if i == 1 then 				if imax > 1 and out_current.builtin == 'hand' then 					out_current.out_next = combos[2]  -- built-in hand can influence next unit in a combination 				end 				if parms.opt_order_out then 					out_current.inout = 'in' 				end 			end 			if out_current.multiple then 				success, item = make_output_multiple(parms, in_unit_table, out_current) 			else 				success, item = make_output_single(parms, in_unit_table, out_current) 			end 			if not success then return false, item end 			outputs[i] = item 		end 		if parms.opt_order_out then 			lhs = outputs[1] 			table.remove(outputs, 1) 		end 		local sep = parms.table_joins and parms.table_joins[2] or parms.join_between 		rhs = table.concat(outputs, sep) 	end 	if flipped or not lhs then 		local input = process_input(parms, in_unit_table) 		if flipped then 			lhs = rhs 			rhs = input 		else 			lhs = input 		end 	end 	if parms.join_before then 		lhs = parms.join_before .. lhs 	end 	local wikitext 	if bad_input_mcode then 		if bad_input_mcode ==  then 			wikitext = lhs 		else 			wikitext = lhs .. message(parms, bad_input_mcode) 		end 	elseif parms.table_joins then 		wikitext = parms.table_joins[1] .. lhs .. parms.table_joins[2] .. rhs 	else 		wikitext = lhs .. parms.joins[1] .. rhs .. parms.joins[2] 	end 	if parms.warnings and not bad_input_mcode then 		wikitext = wikitext .. parms.warnings 	end 	return true, get_styles(parms) .. wikitext, out_unit_table end  local function main_convert(frame) 	-- Do convert, and if needed, do it again with higher default precision. 	local parms = { frame = frame }  -- will hold template arguments, after translation 	set_config(frame.args) 	local success, result = get_parms(parms, frame:getParent().args) 	if success then 		if type(result) ~= 'table' then 			return tostring(result) 		end 		local in_unit_table = result 		local out_unit_table 		for _ = 1, 2 do  -- use counter so cannot get stuck repeating convert 			success, result, out_unit_table = process(parms, in_unit_table, out_unit_table) 			if success and parms.do_convert_again then 				parms.do_convert_again = false 			else 				break 			end 		end 	end 	-- If input=x gives a problem, the result should be just the user input 	-- (if x is a property like P123 it has been replaced with ). 	-- An unknown input unit would display the input and an error message 	-- with success == true at this point. 	-- Also, can have success == false with a message that outputs an empty string. 	if parms.input_text then 		if success and not parms.have_problem then 			return result 		end 		local cat 		if parms.tracking then 			-- Add a tracking category using the given text as the category sort key. 			-- There is currently only one type of tracking, but in principle multiple 			-- items could be tracked, using different sort keys for convenience. 			cat = wanted_category('tracking', parms.tracking) 		end 		return parms.input_text .. (cat or ) 	end 	return success and result or message(parms, result) end  local function _unit(unitcode, options) 	-- Helper function for Module:Val to look up a unit. 	-- Parameter unitcode must be a string to identify the wanted unit. 	-- Parameter options must be nil or a table with optional fields: 	--   value = number (for sort key; default value is 1) 	--   scaled_top = nil for a normal unit, or a number for a unit which is 	--                the denominator of a per unit (for sort key) 	--   si = { 'symbol', 'link' } 	--                (a table with two strings) to make an SI unit 	--                that will be used for the look up 	--   link = true if result should be linked 	--   sort = 'on' or 'debug' if result should include a sort key in a 	--                span element ('debug' makes the key visible) 	--   name = true for the name of the unit instead of the symbol 	--   us = true for the US spelling of the unit, if any 	-- Return nil if unitcode is not a non-empty string. 	-- Otherwise return a table with fields: 	--   text = requested symbol or name of unit, optionally linked 	--   scaled_value = input value adjusted by unit scale; used for sort key 	--   sortspan = span element with sort key like that provided by , 	--     calculated from the result of converting value 	--     to a base unit with scale 1. 	--   unknown = true if the unitcode was not known 	unitcode = strip(unitcode) 	if unitcode == nil or unitcode ==  then 		return nil 	end 	set_config({}) 	linked_pages = {} 	options = options or {} 	local parms = { 		abbr = options.name and 'off' or 'on', 		lk = options.link and 'on' or nil, 		opt_sp_us = options.us and true or nil, 		opt_ignore_error = true,  -- do not add pages using this function to 'what links here' for Module:Convert/extra 		opt_sortable_on = options.sort == 'on' or options.sort == 'debug', 		opt_sortable_debug = options.sort == 'debug', 	} 	if options.si then 		-- Make a dummy table of units (just one unit) for lookup to use. 		-- This makes lookup recognize any SI prefix in the unitcode. 		local symbol = options.si[1] or '?' 		parms.unittable = { [symbol] = { 			_name1 = symbol, 			_name2 = symbol, 			_symbol = symbol, 			utype = symbol, 			scale = symbol == 'g' and 0.001 or 1, 			prefixes = 1, 			default = symbol, 			link = options.si[2], 		}} 	end 	local success, unit_table = lookup(parms, unitcode, 'no_combination') 	if not success then 		unit_table = setmetatable({ 			symbol = unitcode, name2 = unitcode, utype = unitcode, 			scale = 1, default = , defkey = , linkey = '' }, unit_mt) 	end 	local value = tonumber(options.value) or 1 	local clean = tostring(abs(value)) 	local info = { 		value = value, 		altvalue = value, 		singular = (clean == '1'), 		clean = clean, 		show = clean, 	} 	unit_table.inout = 'in' 	unit_table.valinfo = { info } 	local sortspan, scaled_value 	if options.sort then 		sortspan, scaled_value = make_table_or_sort(parms, value, info, unit_table, options.scaled_top) 	end 	return { 		text = make_id(parms, 1, unit_table), 		sortspan = sortspan, 		scaled_value = scaled_value, 		unknown = not success and true or nil, 	} end  return { convert = main_convert, _unit = _unit }