[TeX] amscd unexpected shift

[pkra]

The following example does not match the rendering in real LaTeX.

\require{AMScd}
\begin{equation*}
 \begin{CD}
  \mathcal{O}_Y &@>\varepsilon (\mathcal{O}_Y)>> &L \\
  @VfVV && @VVL\otimes fV \\
  \mathcal{O}_y &@>\varepsilon (\mathcal{O}_y)>> &\,\mathcal{O}_y
 \end{CD} 
\end{equation*}

The arrow pointing down on the left side of the square is not aligned correctly with its top and bottom.

[dpvc]

The issue is with the array tabs (& characters), which I don't think are supposed to be there. (Though you are right, they don't cause problems in LaTeX itself). But

 \begin{CD}
   \mathcal{O}_Y @>\varepsilon (\mathcal{O}_Y)>> L \\
   @VfVV @VVL\otimes fV \\
   \mathcal{O}_y @>\varepsilon (\mathcal{O}_y)>> \,\mathcal{O}_y
 \end{CD} 

produces the desired results. Perhaps the CD environment can simply ignore the ampersands.