Entering tag into version box for diffs

[Roy Smith]

I'm running cvsweb 3.0.6.

Is there some fundamental reason why I can't type a tag into the "tr1" 
and "tr2" fields in the diff request form?  When I do, I get the error 
"Error: Invalid revision: tr1=B-IC-6-2".

I know I can pick B-IC-6-2 out of the pop-up menu, but we've got 
hundreds of tags on most revisions (we tag on every build), so the 
pop-up menu is quite long and unwieldy.  It would be so much easier to 
just type the tag name into the text box.

I'm assuming that all that happens with the content of the text box is 
it's passed along to a "cvs diff -r XXX" command, which is happy to 
accept either numeric or symbolic revisions.