<<< tex \sum_{\substack{ 0<i<m \\ 0<j<n }} P(i,j) >>> native [ EUnder True (ESymbol Op "\8721") (EArray [ AlignCenter ] [ [ [ EGrouped [ ENumber "0" , ESymbol Rel "<" , EIdentifier "i" , ESymbol Rel "<" , EIdentifier "m" ] ] ] , [ [ EGrouped [ ENumber "0" , ESymbol Rel "<" , EIdentifier "j" , ESymbol Rel "<" , EIdentifier "n" ] ] ] ]) , EIdentifier "P" , EDelimited "(" ")" [ Right (EIdentifier "i") , Right (ESymbol Pun ",") , Right (EIdentifier "j") ] ]