msubsup1.native

[ ESubsup (ESymbol Op "\8747") (ENumber "0") (ENumber "1")
, EGrouped
    [ ESuper (EIdentifier "\8519") (EIdentifier "x")
    , ESymbol Ord "\8290"
    , EGrouped [ ESymbol Ord "\8518" , EIdentifier "x" ]
    ]
]