[advising] zero field width message

david (10/13/82)

On occasion files including tables generate the message
"zero field width" when formatted.  The problem is caused
by a table with a column in which the only actual entry
is spanned to another column.  Tbl calculates a width
of zero for the column and passes this on to nroff which
complains.  The immediate solution is to put something in
the column such as a space, or to give the column width