4.2BSD/usr/man/man1/colcrt.1

.TH COLCRT 1 "24 February 1979"
.UC
.SH NAME
colcrt \- filter nroff output for CRT previewing
.SH SYNOPSIS
.B colcrt
[
.B \-
] [
.B \-2
] [
file ...
]
.SH DESCRIPTION
.I Colcrt
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.
.PP
The optional
.B \- 
suppresses all underlining.
It is especially useful for previewing
.I allboxed
tables from
.IR  tbl (1).
.PP
The option
.B \-2
causes 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
.B \-2
option is useful for sending output to the line printer when the output
contains superscripts and subscripts which would otherwise be invisible.
.PP
A typical use of
.I colcrt
would be
.PP
.DT
	tbl exum2.n | nroff \-ms | colcrt \- | more
.SH "SEE ALSO"
nroff/troff(1), col(1), more(1), ul(1)
.SH AUTHOR
William Joy
.SH BUGS
Should fold underlines onto blanks even with the
`\fB\-\fR'
option so that
a true underline character would show; if we did this, however,
.I colcrt
wouldn't get rid of
.I cu'd
underlining
completely.
.PP
Can't back up more than 102 lines.
.PP
General overstriking is lost;
as a special case `|' overstruck with `\-' or underline becomes `+'.
.PP
Lines are trimmed to 132 characters.
.PP
Some provision should be made for processing superscripts and subscripts
in documents which are already double-spaced.