<<< native
[ ESqrt
    (EArray
       [ AlignCenter ]
       [ [ [ EPhantom (EIdentifier "ABCD") ] ]
       , [ [ EPhantom (EIdentifier "ABCD") ] ]
       , [ [ EPhantom (EIdentifier "ABCD") ] ]
       ])
]
>>> tex
\sqrt{\begin{matrix}
\phantom{ABCD} \\
\phantom{ABCD} \\
\phantom{ABCD}
\end{matrix}}