Module:Val
-- For Template:Val, output a number and optional unit.
 -- Format options include scientific and uncertainty notations.
 
 local data_module = 'Module:Val/units'
 local convert_module = 'Module:Convert'
 
 local function valerror(msg, nocat, iswarning)
 	-- Return formatted message text for an error or warning.
 	-- Can append &quot;#FormattingError&quot; to URL of a page with a problem to find it.
 	local anchor = '&lt;span id=&quot;FormattingError&quot;&gt;&lt;/span&gt;'
 	local body, category
 	if nocat or mw.title.getCurrentTitle():inNamespaces(1, 2, 3, 5) then
 		-- No category in Talk, User, User_talk, or Wikipedia_talk.
 		category = ''
 	else
 		category = '[[Category:Pages with incorrect formatting templates use]]'
 	end
 	iswarning = false  -- problems are infrequent so try showing large error so editor will notice
 	if iswarning then
 		body = '&lt;sup class=&quot;noprint Inline-Template&quot; style=&quot;white-space:nowrap;&quot;&gt;' ..
 			'[[Template:Val|&lt;span title=&quot;' ..
 			msg:gsub('&quot;', '&amp;quot;') ..
 			'&quot;&gt;warning&lt;/span&gt;]]&lt;/sup&gt;'
 	else
 		body = '&lt;strong class=&quot;error&quot;&gt;' ..
 			'Error in &amp;#123;&amp;#123;[[Template:val|val]]&amp;#125;&amp;#125;: ' ..
 			msg ..
 			'&lt;/strong&gt;'
 	end
 	return anchor .. body .. category
 end
 
 local range_types = {
 	-- No need for '&amp;nbsp;' because nowrap applies to all output.
 	[&quot;,&quot;]   = &quot;, &quot;,
 	[&quot;by&quot;]  = &quot; by &quot;,
 	[&quot;-&quot;]   = &quot;–&quot;,
 	[&quot;–&quot;]   = &quot;–&quot;,
 	[&quot;and&quot;] = &quot; and &quot;,
 	[&quot;or&quot;]  = &quot; or &quot; ,
 	[&quot;to&quot;]  = &quot; to &quot; ,
 	[&quot;x&quot;]   = &quot; × &quot;,
 	[&quot;×&quot;]   = &quot; × &quot;,
 	[&quot;/&quot;]   = &quot;/&quot;,
 }
 local range_repeat_unit = {
 	-- WP:UNIT wants unit repeated when a &quot;multiply&quot; range is used.
 	[&quot;x&quot;]   = true,
 	[&quot;×&quot;]   = true,
 }
 
 local function extract_item(index, numbers, arg)
 	-- Extract an item from arg and store the result in numbers[index].
 	-- If no argument or if argument is valid, return nil (no error);
 	-- otherwise, return an error message.
 	-- The stored result is:
 	-- * a table for a number (empty if there was no specified number); or
 	-- * a string for range text
 	-- Input like 1e3 is regarded as invalid for all except argument 1
 	-- which accepts e notation as an alternative to the 'e' argument.
 	-- Input commas are removed so 1,234 is the same as 1234.
 	local which = index
 	local function fail(msg)
 		local description
 		if which == 'e' then
 			description = 'exponent parameter (&lt;b&gt;e&lt;/b&gt;)'
 		else
 			description = 'parameter ' .. which
 		end
 		return description .. ' ' .. (msg or 'is not a valid number') .. '.'
 	end
 	local result = {}
 	local range = range_types[arg]
 	if range then
 		if type(index) == 'number' and (index % 2 == 0) then
 			if index == 2 then
 				if numbers[1] and numbers[1].exp then
 					return fail('cannot use a range if the first parameter includes &quot;e&quot;')
 				end
 				numbers.has_ranges = true
 			else
 				if not numbers.has_ranges then
 					return fail('needs a range in parameter 2')
 				end
 			end
 			numbers[index] = range
 			if range_repeat_unit[arg] then
 				-- Any &quot;repeat&quot; range forces unit (if any) to be repeated for all items.
 				numbers.isrepeat = true
 			end
 			return nil
 		end
 		return fail('does not accept a range')
 	end
 	if numbers.has_ranges and type(index) == 'number' and (index % 2 == 0) then
 		return fail('should be a range')
 	end
 	if index == 'e' then
 		local e = numbers[1] and numbers[1].exp
 		if e then
 			if arg then
 				return fail('cannot be used if the first parameter includes &quot;e&quot;')
 			end
 			arg = e
 			which = 1
 		end
 	end
 	if arg and arg ~= '' then
 		arg = arg:gsub(',', '')
 		if arg:sub(1, 1) == '(' and arg:sub(-1) == ')' then
 			result.parens = true
 			arg = arg:sub(2, -2)
 		end
 		local a, b = arg:match('^(.+)[Ee](.+)$')
 		if a then
 			if index == 1 then
 				arg = a
 				result.exp = b
 			else
 				return fail('cannot use e notation')
 			end
 		end
 		local isnegative, propersign, prefix
 		local minus = '−'
 		prefix, arg = arg:match('^(.-)([%d.]+)$')
 		local value = tonumber(arg)
 		if not value then
 			return fail()
 		end
 		if arg:sub(1, 1) == '.' then
 			arg = '0' .. arg
 		end
 		if prefix == '' then
 			-- Ignore.
 		elseif prefix == '±' then
 			-- Display for first number, ignore for others.
 			if index == 1 then
 				propersign = '±'
 			end
 		elseif prefix == '+' then
 			propersign = '+'
 		elseif prefix == '-' or prefix == minus then
 			propersign = minus
 			isnegative = true
 		else
 			return fail()
 		end
 		result.clean = arg
 		result.sign = propersign or ''
 		result.value = isnegative and -value or value
 	end
 	numbers[index] = result
 	return nil  -- no error
 end
 
 local function get_args(numbers, args)
 	-- Extract arguments and store the results in numbers.
 	-- Return nothing (no error) if ok; otherwise, return an error message.
 	for index = 1, 99 do
 		local which = index
 		local arg = args[which]  -- has been trimmed
 		if not arg then
 			which = 'e'
 			arg = args[which]
 		end
 		local msg = extract_item(which, numbers, arg)
 		if msg then
 			return msg
 		end
 		if which == 'e' then
 			break
 		end
 		if index &gt; 19 then
 			return 'too many parameters'
 		end
 	end
 	if numbers.has_ranges and (#numbers % 2 == 0) then
 		return 'need a number after the last parameter because it is a range.'
 	end
 end
 
 local function get_scale(text, ucode)
 	-- Return the value of text as a number, or throw an error.
 	-- This supports extremely basic expressions of the form:
 	--   a / b
 	--   a ^ b
 	-- where a and b are numbers or 'pi'.
 	local n = tonumber(text)
 	if n then
 		return n
 	end
 	n = text:gsub('pi', math.pi)
 	for _, op in ipairs({ '/', '^' }) do
 		local a, b = n:match('^(.-)' .. op .. '(.*)$')
 		if a then
 			a = tonumber(a)
 			b = tonumber(b)
 			if a and b then
 				if op == '/' then
 					return a / b
 				elseif op == '^' then
 					return a ^ b
 				end
 			end
 			break
 		end
 	end
 	error('Unit &quot;' .. ucode .. '&quot; has invalid scale &quot;' .. text .. '&quot;')
 end
 
 local function get_builtin_unit(ucode, definitions)
 	-- Return table of information for the specified built-in unit, or nil if not known.
 	-- Each defined unit code must be followed by two spaces (not tab characters).
 	local _, pos = definitions:find('\n' .. ucode .. '  ', 1, true)
 	if pos then
 		local endline = definitions:find('%s*\n', pos)
 		if endline then
 			local result = {}
 			local n = 0
 			local text = definitions:sub(pos + 1, endline - 1):gsub('%s%s+', '\t')
 			for item in (text .. '\t'):gmatch('(%S.-)\t') do
 				if item == 'ALIAS' then
 					result.alias = true
 				elseif item == 'ANGLE' then
 					result.isangle = true
 					result.nospace = true
 				elseif item == 'NOSPACE' then
 					result.nospace = true
 				elseif item == 'SI' then
 					result.si = true
 				else
 					n = n + 1
 					if n == 1 then
 						local link, symbol = item:match('^%[%[([^|]+)|(.+)%]%]$')
 						if link then
 							result.symbol = symbol
 							result.link = link
 							n = 2
 						else
 							result.symbol = item
 						end
 					elseif n == 2 then
 						result.link = item
 					elseif n == 3 then
 						result.scale_text = item
 						result.scale = get_scale(item, ucode)
 					else
 						result.more_ignored = item
 						break
 					end
 				end
 			end
 			if result.si then
 				local s = result.symbol
 				if ucode == 'mc' .. s or ucode == 'mu' .. s then
 					result.ucode = 'µ' .. s  -- unit code for convert should be this
 				end
 			end
 			if n &gt;= 2 or (n &gt;= 1 and result.alias) then
 				return result
 			end
 			-- Ignore invalid definition, treating it as a comment.
 		end
 	end
 end
 
 local function convert_lookup(ucode, value, scaled_top, want_link, si, options)
 	local lookup = require(convert_module)._unit
 	return lookup(ucode, {
 			value = value,
 			scaled_top = scaled_top,
 			link = want_link,
 			si = si,
 			sort = options.sortable,
 		})
 end
 
 local function get_unit(ucode, value, scaled_top, options)
 	local want_link = options.want_link
 	if scaled_top then
 		want_link = options.want_per_link
 	end
 	local data = mw.loadData(data_module)
 	local result = options.want_longscale and
 		get_builtin_unit(ucode, data.builtin_units_long_scale) or
 		get_builtin_unit(ucode, data.builtin_units)
 	local si, use_convert
 	if result then
 		if result.alias then
 			ucode = result.symbol
 			use_convert = true
 		end
 		if result.scale then
 			-- Setting si means convert will use the unit as given, and the sort key
 			-- will be calculated from the value without any extra scaling that may
 			-- occur if convert found the unit code. For example, if val defines the
 			-- unit 'year' with a scale and if si were not set, convert would also apply
 			-- its own scale because convert knows that a year is 31,557,600 seconds.
 			si = { result.symbol, result.link }
 			value = value * result.scale
 		end
 		if result.si then
 			ucode = result.ucode or ucode
 			si = { result.symbol, result.link }
 			use_convert = true
 		end
 	else
 		result = {}
 		use_convert = true
 	end
 	local convert_unit = convert_lookup(ucode, value, scaled_top, want_link, si, options)
 	result.sortkey = convert_unit.sortspan
 	if use_convert then
 		result.text = convert_unit.text
 		result.scaled_top = convert_unit.scaled_value
 	else
 		if want_link then
 			result.text = '[[' .. result.link .. '|' .. result.symbol .. ']]'
 		else
 			result.text = result.symbol
 		end
 		result.scaled_top = value
 	end
 	return result
 end
 
 local function makeunit(value, options)
 	-- Return table of information for the requested unit and options, or
 	-- return nil if no unit.
 	options = options or {}
 	local unit
 	local ucode = options.u
 	local percode = options.per
 	if ucode then
 		unit = get_unit(ucode, value, nil, options)
 	elseif percode then
 		unit = { nospace = true, scaled_top = value }
 	else
 		return nil
 	end
 	local text = unit.text or ''
 	local sortkey = unit.sortkey
 	if percode then
 		local function bracketed(code, text)
 			return code:find('[*./]') and '(' .. text .. ')' or text
 		end
 		local perunit = get_unit(percode, 1, unit.scaled_top, options)
 		text = (ucode and bracketed(ucode, text) or '') ..
 				'/' .. bracketed(percode, perunit.text)
 		sortkey = perunit.sortkey
 	end
 	if not (unit.nospace or options.nospace) then
 		text = '&amp;nbsp;' .. text
 	end
 	return { text = text, isangle = unit.isangle, sortkey = sortkey }
 end
 
 local function list_units(mode)
 	-- Return wikitext to list the built-in units.
 	-- A unit code should not contain wikimarkup so don't bother escaping.
 	local data = mw.loadData(data_module)
 	local definitions = data.builtin_units .. data.builtin_units_long_scale
 	local last_was_blank = true
 	local n = 0
 	local result = {}
 	local function add(line)
 		if line == '' then
 			last_was_blank = true
 		else
 			if last_was_blank and n &gt; 0 then
 				n = n + 1
 				result[n] = ''
 			end
 			last_was_blank = false
 			n = n + 1
 			result[n] = line
 		end
 	end
 	local si_prefixes = {
 		-- These are the prefixes recognized by convert; u is accepted for micro.
 		y = 'y',
 		z = 'z',
 		a = 'a',
 		f = 'f',
 		p = 'p',
 		n = 'n',
 		u = 'µ',
 		['µ'] = 'µ',
 		m = 'm',
 		c = 'c',
 		d = 'd',
 		da = 'da',
 		h = 'h',
 		k = 'k',
 		M = 'M',
 		G = 'G',
 		T = 'T',
 		P = 'P',
 		E = 'E',
 		Z = 'Z',
 		Y = 'Y',
 	}
 	local function is_valid(ucode, unit)
 		if unit and not unit.more_ignored then
 			assert(type(unit.symbol) == 'string' and unit.symbol ~= '')
 			if unit.alias then
 				if unit.link or unit.scale_text or unit.si then
 					return false
 				end
 			end
 			if unit.si then
 				if unit.scale_text then
 					return false
 				end
 				ucode = unit.ucode or ucode
 				local base = unit.symbol
 				if ucode == base then
 					unit.display = base
 					return true
 				end
 				local plen = #ucode - #base
 				if plen &gt; 0 then
 					local prefix = si_prefixes[ucode:sub(1, plen)]
 					if prefix and ucode:sub(plen + 1) == base then
 						unit.display = prefix .. base
 						return true
 					end
 				end
 			else
 				unit.display = unit.symbol
 				return true
 			end
 		end
 		return false
 	end
 	local lookup = require(convert_module)._unit
 	local function show_convert(ucode, unit)
 		-- If a built-in unit defines a scale or sets the SI flag, any unit defined in
 		-- convert is not used (the scale or SI prefix's scale is used for a sort key).
 		-- If there is no scale or SI flag, and the unit is not defined in convert,
 		-- the sort key may not be correct; this allows such units to be identified.
 		if not (unit.si or unit.scale_text) then
 			if mode == 'convert' then
 				unit.show = not lookup(unit.alias and unit.symbol or ucode).unknown
 				unit.show_text = 'CONVERT'
 			elseif mode == 'unknown' then
 				unit.show = lookup(unit.alias and unit.symbol or ucode).unknown
 				unit.show_text = 'UNKNOWN'
 			elseif not unit.alias then
 				-- Show convert's scale in square brackets ('[1]' for an unknown unit).
 				-- Don't show scale for an alias because it's misleading for temperature
 				-- and an alias is probably not useful for anything else.
 				local scale = lookup(ucode, {value=1, sort='on'}).scaled_value
 				if type(scale) == 'number' then
 					scale = string.format('%.5g', scale):gsub('e%+?(%-?)0*(%d+)', 'e%1%2')
 				else
 					scale = '?'
 				end
 				unit.show = true
 				unit.show_text = '[' .. scale .. ']'
 			end
 		end
 	end
 	for line in definitions:gmatch('([^\n]*)\n') do
 		local pos, _ = line:find('  ', 1, true)
 		if pos then
 			local ucode = line:sub(1, pos - 1)
 			local unit = get_builtin_unit(ucode, '\n' .. line .. '\n')
 			if is_valid(ucode, unit) then
 				show_convert(ucode, unit)
 				local flags, text
 				if unit.alias then
 					text = unit.symbol
 				else
 					text = '[[' .. unit.link .. '|' .. unit.display .. ']]'
 				end
 				if unit.isangle then
 					unit.nospace = nil  -- don't show redundant flag
 				end
 				for _, f in ipairs({
 						{ 'alias', 'ALIAS' },
 						{ 'isangle', 'ANGLE' },
 						{ 'nospace', 'NOSPACE' },
 						{ 'si', 'SI' },
 						{ 'scale_text', unit.scale_text },
 						{ 'show', unit.show_text },
 					}) do
 					if unit[f[1]] then
 						local t = f[2]
 						if t:match('^%u+$') then
 							t = '&lt;small&gt;' .. t .. '&lt;/small&gt;'
 						end
 						if flags then
 							flags = flags .. ' ' .. t
 						else
 							flags = t
 						end
 					end
 				end
 				if flags then
 					text = text .. ' • ' .. flags
 				end
 				add(ucode .. ' = ' .. text .. '&lt;br /&gt;')
 			else
 				add(line .. ' ◆ &lt;b&gt;invalid definition&lt;/b&gt;&lt;br /&gt;')
 			end
 		else
 			add(line)
 		end
 	end
 	return table.concat(result, '\n')
 end
 
 local delimit_groups = require('Module:Gapnum').groups
 local function delimit(sign, numstr, fmt)
 	-- Return sign and numstr (unsigned digits or '.' only) after formatting.
 	-- Four-digit integers are not formatted with gaps.
 	fmt = (fmt or ''):lower()
 	if fmt == 'none' or (fmt == '' and #numstr == 4 and numstr:match('^%d+$')) then
 		return sign .. numstr
 	end
 	-- Group number by integer and decimal parts.
 	-- If there is no decimal part, delimit_groups returns only one table.
 	local ipart, dpart = delimit_groups(numstr)
 	local result
 	if fmt == 'commas' then
 		result = sign .. table.concat(ipart, ',')
 		if dpart then
 			result = result .. '.' .. table.concat(dpart)
 		end
 	else
 		-- Delimit with a small gap by default.
 		local groups = {}
 		groups[1] = table.remove(ipart, 1)
 		for _, v in ipairs(ipart) do
 			table.insert(groups, '&lt;span style=&quot;margin-left:.25em;&quot;&gt;' .. v .. '&lt;/span&gt;')
 		end
 		if dpart then
 			table.insert(groups, '.' .. (table.remove(dpart, 1) or ''))
 			for _, v in ipairs(dpart) do
 				table.insert(groups, '&lt;span style=&quot;margin-left:.25em;&quot;&gt;' .. v .. '&lt;/span&gt;')
 			end
 		end
 		result = sign .. table.concat(groups)
 	end
 	return result
 end
 
 local function sup_sub(sup, sub, align)
 	-- Return the same result as Module:Su except val defaults to align=right.
 	if align == 'l' or align == 'left' then
 		align = 'left'
 	elseif align == 'c' or align == 'center' then
 		align = 'center'
 	else
 		align = 'right'
 	end
 	return '&lt;span style=&quot;display:inline-block;margin-bottom:-0.3em;vertical-align:-0.4em;line-height:1.2em;font-size:85%;text-align:' ..
 		align .. ';&quot;&gt;' .. sup .. '&lt;br /&gt;' .. sub .. '&lt;/span&gt;'
 end
 
 local function range_text(items, unit_table, options)
 	local fmt = options.fmt
 	local nend = items.nend or ''
 	if items.isrepeat or unit_table.isangle then
 		nend = nend .. unit_table.text
 	end
 	local text = ''
 	for i = 1, #items do
 		if i % 2 == 0 then
 			text = text .. items[i]
 		else
 			text = text .. delimit(items[i].sign, items[i].clean, fmt) .. nend
 		end
 	end
 	return text
 end
 
 local function uncertainty_text(uncertainty, unit_table, options)
 	local angle, text, need_parens
 	if unit_table.isangle then
 		angle = unit_table.text
 	end
 	local upper = uncertainty.upper or {}
 	local lower = uncertainty.lower or {}
 	local uncU = upper.clean
 	if uncU then
 		local fmt = options.fmt
 		local uncL = lower.clean
 		if uncL then
 			uncU = delimit('+', uncU, fmt) .. (upper.errend or '')
 			uncL = delimit('−', uncL, fmt) .. (lower.errend or '')
 			if angle then
 				uncU = uncU .. angle
 				uncL = uncL .. angle
 			end
 			text = (angle or '') ..
 				'&lt;span style=&quot;margin-left:0.3em;&quot;&gt;' ..
 				sup_sub(uncU, uncL, options.align) ..
 				'&lt;/span&gt;'
 		else
 			if upper.parens then
 				text = '(' .. uncU .. ')'  -- old template did not delimit
 			else
 				text = (angle or '') ..
 					'&lt;span style=&quot;margin-left:0.3em;margin-right:0.15em;&quot;&gt;±&lt;/span&gt;' ..
 					delimit('', uncU, fmt)
 				need_parens = true
 			end
 			if uncertainty.errend then
 				text = text .. uncertainty.errend
 			end
 			if angle then
 				text = text .. angle
 			end
 		end
 	else
 		if angle then
 			text = angle
 		end
 	end
 	return text, need_parens
 end
 
 local function _main(values, unit_spec, options)
 	if options.sandbox then
 		data_module = data_module .. '/sandbox'
 		convert_module = convert_module .. '/sandbox'
 	end
 	local action = options.action
 	if action then
 		if action == 'list' then
 			-- Kludge: am using the align parameter (a=xxx) for type of list.
 			return list_units(options.align)
 		end
 		return valerror('invalid action &quot;' .. action .. '&quot;.', options.nocat)
 	end
 	local number = values.number or (values.numbers and values.numbers[1]) or {}
 	local e_10 = options.e or {}
 	local novalue = (number.value == nil and e_10.clean == nil)
 	local fmt = options.fmt
 	local want_sort = true
 	local sortable = options.sortable
 	if sortable == 'off' or (sortable == nil and novalue) then
 		want_sort = false
 	elseif sortable == 'debug' then
 		-- Same as sortable = 'on' but the sort key is displayed.
 	else
 		sortable = 'on'
 	end
 	local sort_value = 1
 	if want_sort then
 		sort_value = number.value or 1
 		if e_10.value and sort_value ~= 0 then
 			-- The 'if' avoids {{val|0|e=1234}} giving an invalid sort_value due to overflow.
 			sort_value = sort_value * 10^e_10.value
 		end
 	end
 	local unit_table = makeunit(sort_value, {
 						u = unit_spec.u,
 						want_link = unit_spec.want_link,
 						per = unit_spec.per,
 						want_per_link = unit_spec.want_per_link,
 						nospace = novalue,
 						want_longscale = unit_spec.want_longscale,
 						sortable = sortable,
 					})
 	local sortkey
 	if unit_table then
 		if want_sort then
 			sortkey = unit_table.sortkey
 		end
 	else
 		unit_table = { text = '' }
 		if want_sort then
 			sortkey = convert_lookup('dummy', sort_value, nil, nil, nil, { sortable = sortable }).sortspan
 		end
 	end
 	local final_unit = unit_table.isangle and '' or unit_table.text
 	local e_text, n_text, need_parens
 	local uncertainty = values.uncertainty
 	if uncertainty then
 		if number.clean then
 			n_text = delimit(number.sign, number.clean, fmt) .. (number.nend or '')
 			local text
 			text, need_parens = uncertainty_text(uncertainty, unit_table, options)
 			if text then
 				n_text = n_text .. text
 			end
 		else
 			n_text = ''
 		end
 	else
 		if values.numbers.isrepeat then
 			final_unit = ''
 		end
 		n_text = range_text(values.numbers, unit_table, options)
 		need_parens = true
 	end
 	if e_10.clean then
 		if need_parens then
 			n_text = '(' .. n_text .. ')'
 		end
 		e_text = '10&lt;sup&gt;' .. delimit(e_10.sign, e_10.clean, fmt) .. '&lt;/sup&gt;'
 		if number.clean then
 			e_text = '&lt;span style=&quot;margin-left:0.25em;margin-right:0.15em;&quot;&gt;×&lt;/span&gt;' .. e_text
 		end
 	else
 		e_text = ''
 	end
 	local result =
 		(sortkey or '') ..
 		(options.prefix or '') ..
 		n_text ..
 		e_text ..
 		final_unit ..
 		(options.suffix or '')
 	if result ~= '' then
 		result = '&lt;span class=&quot;nowrap&quot;&gt;' .. result .. '&lt;/span&gt;'
 	end
 	return result .. (options.warning or '')
 end
 
 local function check_parameters(args, has_ranges, nocat)
 	-- Return warning text for the first problem parameter found, or nothing if ok.
 	local whitelist = {
 		a = true,
 		action = true,
 		debug = true,
 		e = true,
 		['end'] = true,
 		errend = true,
 		['+errend'] = true,
 		['-errend'] = true,
 		fmt = true,
 		['long scale'] = true,
 		long_scale = true,
 		longscale = true,
 		nocategory = true,
 		p = true,
 		s = true,
 		sortable = true,
 		u = true,
 		ul = true,
 		up = true,
 		upl = true,
 	}
 	for k, v in pairs(args) do
 		if type(k) == 'string' and not whitelist[k] then
 			local warning = 'Val parameter &quot;' .. k .. '=' .. v .. '&quot; is not supported'
 			return valerror(warning, nocat, true)
 		end
 	end
 	if not has_ranges and args[4] then
 		return valerror('Val parameter 4 ignored', nocat, true)
 	end
 end
 
 local function main(frame)
 	local getArgs = require('Module:Arguments').getArgs
 	local args = getArgs(frame, {wrappers = { 'Template:Val' }})
 	local nocat = args.nocategory
 	local numbers = {}  -- table of number tables, perhaps with range text
 	local msg = get_args(numbers, args)
 	if msg then
 		return valerror(msg, nocat)
 	end
 	if args.u and args.ul then
 		return valerror('unit (&lt;b&gt;u&lt;/b&gt;) and unit with link (&lt;b&gt;ul&lt;/b&gt;) are both specified, only one is allowed.', nocat)
 	end
 	if args.up and args.upl then
 		return valerror('unit per (&lt;b&gt;up&lt;/b&gt;) and unit per with link (&lt;b&gt;upl&lt;/b&gt;) are both specified, only one is allowed.', nocat)
 	end
 	local values
 	if numbers.has_ranges then
 		-- Multiple values with range separators but no uncertainty.
 		numbers.nend = args['end']
 		values = {
 			numbers = numbers,
 		}
 	else
 		-- A single value with optional uncertainty.
 		local function setfield(i, dst, src)
 			local v = args[src]
 			if v then
 				if numbers[i] then
 					numbers[i][dst] = v
 				else
 					numbers[i] = { [dst] = v }
 				end
 			end
 		end
 		setfield(1, 'nend', 'end')
 		setfield(2, 'errend', '+errend')
 		setfield(3, 'errend', '-errend')
 		values = {
 			number = numbers[1],
 			uncertainty = {
 				upper = numbers[2],
 				lower = numbers[3],
 				errend = args.errend,
 			}
 		}
 	end
 	local unit_spec = {
 			u = args.ul or args.u,
 			want_link = args.ul ~= nil,
 			per = args.upl or args.up,
 			want_per_link = args.upl ~= nil,
 			want_longscale = (args.longscale or args.long_scale or args['long scale']) == 'on',
 		}
 	local options = {
 			action = args.action,
 			align = args.a,
 			e = numbers.e,
 			fmt = args.fmt,
 			nocat = nocat,
 			prefix = args.p,
 			sandbox = string.find(frame:getTitle(), 'sandbox', 1, true) ~= nil,
 			sortable = args.sortable or (args.debug == 'yes' and 'debug' or nil),
 			suffix = args.s,
 			warning = check_parameters(args, numbers.has_ranges, nocat),
 		}
 	return _main(values, unit_spec, options)
 end