Re: [dalias@aerifal.cx: ansi-term \e[J causes spurious newline [revised report]]

[Miles Bader <miles.bader@necel.com>]

Dan Nicolaescu <dann@ics.uci.edu> writes:
>   > Is it the escape sequence "\e[J" actually undefined on a real terminal
>   > in that case, or is merely the more abstract "ed" terminfo capability
>   > which is undefined in that case?
>
> I am not sure what the question is... :-(
> In any case I am not aware of any documentation for the different
> escape sequences other than terminfo (or the terminal emulator
> actual code, if that counts as documentation).

I mean that you described the preconditions of the terminfo "ed"
capability, but that's not what term.el seems to be modelled after (to
degree that it's modelled after anything :-).  Terminfo is an
abstraction, and so tries to restrict the assumptions people make about
capabilities to some practical common denominator of the many types of
terminals it supports -- however many programs do not use terminfo; for
instance they may directly use ANSI escape sequences instead.

term.el says:

   ;;; It emulates (most of the features of) a VT100/ANSI-style terminal.

Elsewhere it mentions xterm in passing, and that's probably the most
relevant modern example of a "VT100/ANSI-style terminal".

I'm not saying it should exactly emulate any existing terminal -- that's
probably impractical -- but neither should it restrict its emulation to
only those sequences terminfo might produce.  For term.el to be
practical, we should care whether term.el follows common xterm and
VT100/ansi practice, even in cases where the behavior in question would
never be produced by terminfo.

-Miles

-- 
My books focus on timeless truths.  -- Donald Knuth