empty table cells

I've got a document with an informaltable with empty entries and
the 1.61.2 xhtml stylesheets produce odd results. When I look at the
resultant html in a browser I see a '^A' in the empty cells.
The stylesheet seems to output a   for an empty cell.

Any ideas on how to avoid this?

BTW is there a list somewhere of the meaning of the &#xxx; entities?

Thanks,

Brian