rec-mlabeledtr.test

<<< native
[ EArray
    [ AlignCenter ]
    [ [ [ EGrouped
            [ EIdentifier "E"
            , ESymbol Rel "="
            , EGrouped
                [ EIdentifier "m"
                , ESymbol Ord "\8290"
                , ESuper (EIdentifier "c") (ENumber "2")
                ]
            ]
        ]
      ]
    ]
]
>>> tex
\begin{matrix}
{E = {mc^{2}}}
\end{matrix}