RE: Terminal Graphics Draft 2

From: Frank da Cruz (fdc@watsun.cc.columbia.edu)
Date: Thu Oct 08 1998 - 12:48:37 EDT


> > > E024 84 IND IN Symbol for Index (3)
> > > E025 85 NEL NL Symbol for Next Line
> > >
> > newline??? again?
>
> I agree with Kent. Shouldn't this simply be:
>
> U+2424 SYMBOL FOR NEWLINE
>
That depends on what the (unstated) semantics are for U+2424.
I expect it simply represents a "line terminator", like LF in
UNIX, CR on the Macintosh, or CRLF in DOS.

NEL stands for Next Line (not Newline). The definition of NEL
in ISO 6429 [8.3.87] is rather complex: "The effect of NEL
depends on the setting of the DEVICE COMPONENT SELECT MODE
(DCSM) and on the parameter value of SELECT IMPLICIT MOVEMENT
DIRECTION (SIMD)." Several paragraphs go on to explain this.

Confusingly, terminals that support C1 controls and that also
use 2-character abbreviations for them abbreviate NEL as NL.
However, the VT220 class of terminals actually puts "NEL" on
the screen in display-controls mode. All this in contrast to
EBCDIC, which defines an actual NL character, which I doubt
carries the ISO NEL semantics.

- Frank

P.S. Sorry for getting your name backwards, Kent. And for
omitting Geoffrey Waigh from the acknowledgements. Both errors
fixed in my working copy. Also, no more posting long drafts;
just pointers from now on.



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