bug#3035: 23.0.92; doc, terminology for graphics, display, terminal, etc.

[Drew Adams]

> > > > > > 2. In the Elisp manual, I see the use of terms such as 
> > > > > > "graphical terminal", "graphicical display" (also
> > > > > > "graphics display"), "(non-)graphics-capable display",
> > > > > > "text terminals" (opposed to graphical), "graphic
> > > > > > characters", and "graphical attributes", without any
> > > > > > real explanation or definition.
> > > > > 
> > > > > From the node "Frames", near the beginning:...
> > > > > If this is not good enough, please tell what is missing.
> > > > 
> > > > Yes, that helps wrt "graphical terminal" and "text 
> > > > terminal" (but not with the rest).
> > > 
> > > But that's what your Item 2 (above) was all about: the distinction
> > > between text and graphical terminals.  What else is needed?
> > 
> > Yes and no. Yes for these: "graphical display", "graphics 
> > display", and "graphics-capable display", if one understands
> > that they are synonymous.
> 
> They are synonymous.
> 
> > Likewise, for "text terminals" and "non-graphical-capable displays".
> 
> Also synonyms.
> 
> > It's also not clear to me how "graphic characters" and 
> > "graphical attributes" fit in with the others. For instance,
> > are they implied by "graphical display"?
> > Does any of them alone imply "graphical display"? What does 
> > each of them mean?
> 
> "graphic characters" have nothing to do with displays or terminals.
> They are named "graphic" because they match the [:graph:] regexp.
> 
> The only place I found "graphical attributes" is in the context of
> face attributes.  Since faces are supported on text terminals as well,
> these also don't have any direct relation to GUI vs TTY displays.

OK, so the point for the doc is that these things could perhaps be mentioned. I
appreciate knowing these things, but others might have the same questions or be
similarly confused.

Alternatively this possible confusion could perhaps be avoided, by using the
same term throughout (e.g. always "text terminal", not "non-graphical-capable
display").

> > you might also consider using bold instead of quoting, for defined
> > terms (another item we discussed). That is a convention often used
> > in technical doc.
> 
> I don't think it's a good idea to show bold in Info when it comes out
> as slanted in print.  And making this change in the printed output as
> well would be unwise, IMO, as this is a very old and well-known
> convention of Texinfo.

I see. But you said the same thing about emphasis (_foo_). If both "some
quotation" and _something emphasized_ appear as slanted text in print, then how
does a reader distinguish these uses?

> > Maybe a glossary in Elisp would be helpful too?
> 
> Probably.