<<< native [ EDelimited "|" "|" [ Right (EArray [ AlignCenter ] [ [ [ EIdentifier "U" ] ] , [ [ EIdentifier "V" ] ] ]) ] , ESymbol Rel "=" , EDelimited "\8214" "\8214" [ Right (EArray [ AlignCenter ] [ [ [ EIdentifier "U" ] ] , [ [ EIdentifier "V" ] ] ]) ] ] >>> mml $$\left|\begin{array}{c}\hfill U\hfill \\ \hfill V\hfill \end{array}\right|=\Vert \begin{array}{c}\hfill U\hfill \\ \hfill V\hfill \end{array}\Vert$$