"Richard A. O'Keefe" <ok at cs.otago.ac.nz> wrote:
> This is confusing.
>     The ASCII character called "backspace (BS)" has code 8.


Peter Crowther <peter.crowther at networkinference.com> wrote:
> Er... no.  


Hans-Martin Mosner <hmm at heeg.de> wrote:
> Lex, what have you been smoking?


Thank you all for the cases in point!   I've read way more about this
stupid issue than is probably healthy, and I truly have been convinced
that character 127, "DEL", is better mapping for the backspace key. 
That doesn't mean it's right, but it just shows you that 

"BS" was traditionally for moving to the left "without" deleting.  You
could use it to underline text, for example:

	a^H_b^H_c^H_

If you wanted to actually rub out a character, you couldn't!  However,
on a *punch card* you sort of could: back up (with the BS key,
probably), and hit DEL, which has all the bits turned on.  Now your
punchcard has an entry that has been filled with ones, which if I've
heard correctly most punchcard readers would ignore.

But let's blast forward  in time to CRT-based text terminals.  On a CRT
you can do true rubout.  However, using BS for that purpose is probably
not the best: we may want to emulate BS tricks from old software.  (In
fact, the Unix manpage software does!)  Logical reasons aside, we may
*still* want to go along with what the DEC VT100 did, just to have some
rule to be consistent with.  In fact the VT100 used -- care to guess? --
character code 127.

I'll shut up now.  If you want to read more, here are some pages:

	http://www.ibb.net/~anne/keyboard.html
	http://bugs.debian.org/cgi-bin/bugreport.cgi?archive=no\&bug=2313


Clearly, consensus on the correct behavior is nowhere in sight.  
Happily, we don't need to bother with it.  Most configurations seem to
at least agree that the character at the top-right of the main part of
the keyboard is called "Backspace", even when the keyboard labels the
key physical "delete".   Thus, X11 software like the Unix Squeak VM can
just watch for "Backspace" versus "Delete".


Lex