Re: [OT] What is DEL for?

From: John Cowan (
Date: Wed Feb 21 2001 - 11:51:54 EST

Marco Cimarosti wrote:

> What is the function of ASCII control code 0x7F (DEL) in text interchange?
> Particularly, what effect or interpretation might it have in communication
> protocols, terminal protocols and, especially, inside text files?

In general it has none. Some systems interpret it (erroneously) as
either "cancel previous character" (usually BS) or "interrupt process"
(usually ^C).

> My interest is about the function of this character in *contemporary*
> platforms and software, although I wouldn't dislike historical information,
> as far as it is clearly flagged as such.

Historically it was used to "rub out" existing characters on punched
paper tape. Because it had all bits set (from a 7-bit viewpoint), it
could always be punched over any other character without the need of
changing holes to non-holes. Therefore, punched paper tape systems
ignored it.

There is / one art             || John Cowan <>
no more / no less              ||
to do / all things             ||
with art- / lessness           \\ -- Piet Hein

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