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Path: utzoo!utgpu!water!watnot!watmath!clyde!rutgers!husc6!seismo!munnari!otc!metro!basser!john
From: john@basser.UUCP
Newsgroups: comp.unix.wizards
Subject: Re: Control Characters in nroff
Message-ID: <888@basser.oz>
Date: Thu, 19-Mar-87 14:45:35 EST
Article-I.D.: basser.888
Posted: Thu Mar 19 14:45:35 1987
Date-Received: Sun, 22-Mar-87 23:18:17 EST
References: <207@motbos.UUCP> <7786@utzoo.UUCP>
Reply-To: john@basser.oz (John Mackin)
Organization: Dept of Comp Sci, Uni of Sydney, Australia
Lines: 37
Summary: some can be input, but they can't be output

In article <7786@utzoo.UUCP> henry@utzoo.UUCP (Henry Spencer) writes:

  [ here he quotes an anonymous person: ]
> > Does anyone out there have experience in embedding non-printing ASCII
> > characters in an nroff file ?  For example, the NEC Laser Printers use an
> > ASCII FS (Form Separator) character to control various font / print modes.
> > I have had no problems embedding an ASCII ESC (Escape)...
> 
> I'm rather surprised that you got away with ESC.  Nroff/troff converts its
> input entirely into its own internal alphabet while processing, and if the
> character you want isn't in the internal alphabet, you're up the creek.

That's correct.  I just thought I'd supply the full story.  From
the ``NROFF/TROFF User's Manual'', by Joseph Osanna, section 10.1:

    _Input character translations._  Ways of inputting the
    graphic character set were discussed in sec. 2.1.  The
    ASCII control characters horizontal tab (sec. 9.3), SOH
    (sec 9.1), and backspace (sec. 10.3) are discussed elsewhere.
    The newline delimits input lines.  In addition, STX, ETX,
    ENQ, ACK and BEL are accepted, and may be used as delimiters
    or translated into a graphic with _tr_ (sec. 10.5).  _All_
    others are ignored.

I too am surprised, in view of this, that the original poster ``had no
problems embedding an ESC.''  Certainly it is ignored by both nroff
and troff on our machine.  I suggest that one should certainly not
rely on that behavior; any nroff exhibiting it is, by the User's
Manual, broken.

John Mackin, Basser Department of Computer Science,
	     University of Sydney, Sydney, Australia

john@basser.oz.AU (john%basser.oz@SEISMO.CSS.GOV)
{seismo,hplabs,mcvax,ukc,nttlab}!munnari!basser.oz!john

Copyright 1987 John J. Mackin.  Restricted redistribution prohibited.