RE: [OT] What is DEL for?

From: Jungshik Shin (
Date: Thu Feb 22 2001 - 08:32:27 EST

On Thu, 22 Feb 2001, Marco Cimarosti wrote:

> Frank da Cruz wrote:

> > DEL does indeed have a use in plain text files that are encoded with
> > Shift-In / Shift-Out to switch between left and right halves of (say)
> > ISO 8859-1 without having to actually put 8-bit characters in the
> > file.
> This sounds quite double-byte Greek to me but, if my understanding is
> correct, it could be an interesting precedent.
> This is what I think I understood:
> - Same 8-bit character sets (e.g. Latin-1) may be encoded in 7-bit bytes.
> - The same values 0x20..0x7F are used both to represent characters
> 0x20..0x7F themselves (the "left half", I guess) and characters 0xA0..0xFF
> (the "right half", I guess).
> - The Shift-In and Shift-Out control characters (0x0F and 0x0E) are inserted
> in the text to signal whether or not, from that point onwards, 0x80 has to
> be added to each byte's value.
> - In this scheme, DEL (0x7F) is used to represent both character 0x7F itself

Not at the same time. 02/00 and 07/15 are used to represent U00A0 and
U00FF ONLY when the right half of ISO 8859-1 (there is the name for this,
but I forgot) is designated as G1(or G2/G3) (in advance) and (later)
invoked onto GL with SO (or LS2/LS3). The meaning of 07/15 and 02/00
are preserved when ISO 646 is invoked on GL, I guess.

> If you ACK my understanding, the question is: how do these 0x7F bytes
> (representing 0xFF characters) interact with terminals/host communication?

I think a decent terminal (emulator) with the proper understanding of
ISO-2022 would not get confused :-)

> > Ditto for "higher" levels of ISO-2022 character-set invocation (LS3, etc).
> Could I find ISO-2022 on-line (or an unofficial explanation of it)?

The answer was given yesterday :-). Pls, go to <> and
look for ECMA-35 (which is ISO-2022). Unlike ISO, ECMA has made their
standard documents available on-line for quite a while.

Jungshik Shin

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