texmath-0.13.2: test/writer/starmath/substack.test

<<< 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"
, ESymbol Open "("
, EIdentifier "i"
, ESymbol Pun ","
, EIdentifier "j"
, ESymbol Close ")"
]
>>> starmath
sum from matrix { {0 < i < m} ## {0 < j < n} } P(i, j)