[Groff] conditionals inside a table?

[Anton Shterenlikht]

I want to make a document that can give good
ascii and Postscript results. I found that I need
to adjust the formating of tables. I'm trying to
to this with .ie/.el like this:

   10   .TS H
   11   expand,center;
   12   .ie t lw(0.5i) lw(0.01i) lw(0.5i) lw(2.5i) lw(1.4i).
   13   .el lw(1i) lw(0.2i) lw(1i) lw(5i) lw(3i).

However, it seems tbl doesn't understand this:

tbl:wish.1:12: `.' not last character on line
tbl:wish.1:12: giving up on this table

Please advise

Thanks

Anton