[Xy-pic] newbie question

[mike]

Hi

I'm using "Xy-pic version 3.7 <1999/02/16>".  I have the following example:

\xymatrix @R=1pc {
1,1 & 1,2 & 1,3 \\
2,1 & 2,2 & 2,3 & \\
3,1 & 3,2 & 3,3
\save "2,2"."3,3"!C="x99"*[F.]\frm{_\}}
\restore}

I understand that the "*[F.]" bit gives me the dotted frame but I want 
an invisible frame.  I've done it this way because of the following 
"\frm{_\}}" bit which is what I'm really after, i.e., I just want a 
downward facing brace from "2,2" to "3,3".  If I get rid of "*[F.]" I 
lose the bracket even with the "\frm{_\}}" bit still there.

Can someone tell me how to do this?

Cheers,
Mike