NAME

     bsfilt, colcrt - a colcrt-like backspace filter


SYNOPSIS

     bsfilt [ - ] [ -U ] [ file ... ]


DESCRIPTION

     Bsfilt filters backspace sequences from  the  input  file(s)
     (standard  input  if none) in an approximation of colcrt(1).
     Both the backspace and  the  character  it  returns  to  are
     removed,  unless they form an underline sequence.  Underline
     sequences are treated according to the settings of the - and
     -U options.


OPTIONS

     -    specifies that no underlining of any kind is to be pro-
          pagated.   Without this option or the -U option, bsfilt
          approximates underlining with minus signs (`-') in fol-
          lowing lines.

     -U   specifies that underlining with  underscore  (`_')  and
          backspace (` character sequences is permitted.


SEE ALSO

     cawf(1), colcrt(1) and nroff(1).


DIAGNOSTICS

     Diagnostic messages are  delivered  to  the  standard  error
     file.


HISTORY

     Vic Abell of Purdue University wrote bsfilt to have a  back-
     space  filter  for  cawf(1)  that is independent of licensed
     source code.


BUGS

     The maximum length of a line that  can  be  underlined  with
     minus signs is fixed.

     Bsfilt does not examine the characters that are being  over-
     printed  via  backspace operations.  Thus, overprinting that
     is intended to form a new character from  several  different
     ones  is  ineffective  and  only  the  last character of the
     sequence is propagated - e. g., ``o^H+'', intended  to  look
     like a bullet, is reduced to `+'.