Termcap Standardization

[Lyle McElhaney]

> >   The line drawing character set definitions are equally confused.  Many
> > termcap entries just don't define characters that are there at all, and
> > some leave out entries like GC, GL, and GR.  Many terminals that have the
> 
> Terminal graphics are really outside the scope of Termcap. Terminfo can
> probably handle them, but Termcap was never designed to deal with anything
> but BL through TILDE.
>                                It is probably
> inadvisable to require graphics character sets in a termcap program, as many
> terminals don't support them... certainly damn few terminal emulators do.

Well, its true that termcap was designed before the line drawing character
sets were commonly available on terminals, but it doesn't seem too hard to
get them into use through termcap. The set of caps that I use in my work
with the Rand editor are:

	Gs - turn on line-drawing mode  Ge - turn it off
	Tl - Upper left corner          Tr - top right corner
	Bl - Bottom left corner         Br - bottom right corner
	Vl - vertical line              Hl - horizontal line
	Lj - left join                  Rj - right join
	Tj - top join                   Bj - bottom join
	Cj - center join (cross)        Xc - some other distinct line-drawing
						mode character

(Most of this was posted a long time back by eric at aerospace - credit where
due.) This works well on vt100 types, freedom 100's, and every other line-
drawing set I've seen (except the ADM 11 - would you believe magic cookies
in the line-drawing stuff?).

Note, this is not a general purpose graphics interface - just horizontal
and vertical lines with corners and joins, for drawing windows. Its well
within the capabilities of the design of termcap.

A general question on the termcap function tputs: what is the easiest way
to defeat the delay feature (avoiding the delays that are represented
by the numbers on the front of the cap)? If the terminal is running in
cbreak mode, the delays aren't needed (assuming some flow control mechanism
alive in cbreak mode).

It is unfortunate that there is no single authority on termcap as there is
on terminfo (although Doug Gwynn does fill that function as well as it can
be filled in the chaos).  Adding caps (like the line-drawing set above) is
purely ad-hoc; no where exists where they (or any reasonable facsimile)
are accepted and made "standard", so termcap entries containing them are
also non-standard, and aren't acceptable in general.  Since there are no
entries published with them, everyone invents their own,.....and so on.