The
utility provides virtual half-line and reverse line feed sequences for terminals without such capability, and on which overstriking is destructive. Half-line characters and underlining (changed to dashing `-') are placed on new lines in between the normal output lines.
The following options are available:
Suppress all underlining. This option is especially useful for previewing
tables from
Cause all half-lines to be printed, effectively double spacing the output. Normally, a minimal space output format is used which will suppress empty lines. The program never suppresses two consecutive empty lines, however. The
option is useful for sending output to the line printer when the output contains superscripts and subscripts which would otherwise be invisible.
The
and
environment variables affect the execution of
as described in
A typical use of
would be
tbl exum2.n | nroff -ms | colcrt - | more
The
command appeared in
Should fold underlines onto blanks even with the
option so that a true underline character would show.
Cannot back up more than 102 lines.
General overstriking is lost; as a special case
overstruck with
or underline becomes
Lines are trimmed to 132 characters.
Some provision should be made for processing superscripts and subscripts in documents which are already double-spaced.
Characters that take up more than one column position may not be underlined correctly.