RE: Terminal Graphics Draft 2

From: Frank da Cruz (
Date: Thu Oct 08 1998 - 13:25:02 EDT

> > > ... Shouldn't this simply be:
> > >
> > >
> > 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.
> No, it is a graphic symbol for the Newline control, as for
> example, as represented on terminals--at least as I understand
> it. It is not a substitute for \n (which would, as you point
> out, be LF, CR, or CRLF, depending on platform).
But what is the Newline control? As far as I know, it is defined
only in EBCDIC. It is not defined anywhere in ASCII, ISO 646,
or ISO 6429. In fact, unlike all the other C0 controls in the
U+2400 block, it is not defined in any ISO registered control set.
Do you happen to know the story behind its original inclusion in
this block?

> I doubt there is ever a contrast [between Newline and Next Line].
> Yes, there may be a contrast
> in the details of implementation, but that is besides the point
> for a graphic representing the control. That would be like
> claiming that we needed separate graphic symbols to represent
> a LF, depending on platform-specific differences in the details
> of its semantics.
> As for any disunification, correctness of discrimination needs
> to be weighed against the level of confusion and ambiguity
> of usage that may result from trying to distinguish via
> characters things that most people cannot discriminate in use.
I can't think of any connections where both NL and NEL would be
used in the same data stream, since data streams tend to be
either ASCII/ISO or EBCDIC, but not a mixture.

However, real terminals (VT220-520) print "NEL" when in display-
controls mode, so why make an exception to the rule of printing
the actual name in this one case? I think this would be more
confusing than doing what the actual terminal does. Especially
considering the "metareferences" we might make to these characters
in Unicode texts; e.g. "An ISO data stream will show the [NEL]
character, whereas an EBCDIC data stream will show the [NL]

I'm sure we could also find other examples of control characters
in the C1 and EBCDIC sets whose semantics are the same or close
but whose names differ; I don't think that means we should unify
them. The purpose of "display controls" is to show the customary
and familiar mnemonic for each control character in its context so
people can read them easily.

- Frank

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