local p = {}

function p.tracking(frame)

	local res = ''

	local isNRHP = false

	local hasNRHPbox = false

	local heritage = frame.args.heritage or ''

	if heritage == '' then

	elseif (heritage:match('National Register of Historic Places') or

		heritage:match('NRHP') ) then

		res = res .. '[[Category:Pages using infobox lighthouse with NRHP heritage]]'

		isNRHP = true

	end

	

	for k, v in pairs( frame:getParent().args ) do

		if k and k == 'module' then

			if v and v:match('<tr') then

				if v:match('National Register of Historic Places') or v:match('NRHP') 

					or v:match('U.S. Historic district') 

					or v:match('U.S. National Register of Historic Places') then

					hasNRHPbox = true

				end

			end

		end

	end

	if hasNRHPbox == false and isNRHP == true then

		res = res .. '[[Category:Pages using infobox lighthouse with NRHP heritage|‽]]'

	end

	if hasNRHPbox == true and isNRHP == false then

		res = res .. '[[Category:Pages using infobox lighthouse with NRHP heritage|¶]]'

	end

	return res

end

return p