Section: User Commands (1)
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 allboxed tables from tbl?(1).:
- 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 -2 option is useful for sending output to the line printer when the output contains superscripts and subscripts which would otherwise be invisible.:
A typical use of would be
tbl exum2.n | nroff -ms | colcrt - | more
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.