NAME
   colcrt - filter nroff output for CRT previewing

SYNOPSIS
   colcrt [-] [-2] [file ...]

DESCRIPTION
   Colcrt provides virtual half-line and reverse line feed sequences for
   terminals without such capability, and on which overstriking is destruc-
   tive. Half-line characters and underlining (changed to dashing `-') are
   placed on new lines in between the normal output lines.

   Available options:

   -    Suppress all underlining. This option is especially useful for
    previewing allboxed tables from tbl(1).

   -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 -2 option is useful
    for sending output to the line printer when the output contains
    superscripts and subscripts which would otherwise be invisible.

EXAMPLES
   A typical use of colcrt would be

   tbl exum2.n | nroff -ms | colcrt - | more

SEE ALSO
  nroff(1),troff(1),col(1),more(1),ul(1)

BUGS
   Should fold underlines onto blanks even with the '-' option so that a
   true underline character would show.

   Can't 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.

HISTORY
   The colcrt command appeared in 3.0BSD.