Changes

local text = return externallinkid(frame, {link="Amazon Standard Identification Number",label="ASIN",prefix="//www.amazon."..domain.."/dp/",id=id})--[=[ this applies to DOI not ASIN if ( string.sub(id,1,3) ~= "10." ) then text = text .. "[[Category:Pages with DOI errors]]" end ]=] return text

local code = string.id:sub(id,string.length(id)-1,-1)