Re: Adequacy of min-colors thresholds

On Tuesday, July 14th, 2026 at 10:18 AM, Heime <[email protected]>=
 wrote:

>=20
> On Tuesday, July 14th, 2026 at 9:25 AM, Stephen Berman <stephen.berman@gm=
x.net> wrote:
>=20
> > On Mon, 13 Jul 2026 19:42:52 +0000 Heime <[email protected]> w=
rote:
> >
> > > On Tuesday, July 14th, 2026 at 6:25 AM, Eli Zaretskii <[email protected]> =
wrote:
> > >
> > >> > Date: Mon, 13 Jul 2026 17:44:17 +0000
> > >> > From: Heime <[email protected]>
> > [...]
> > >> > And what is a (min-colors 88) exactly?
> > >>
> > >> Any terminal that supports at least 88 colors.
> > >
> > > Why the chosen 88?  Is that some special terminal support?
> >
> > See https://www.invisible-island.net/xterm/xterm.faq.html#color_by_numb=
er:
> >
> >   In development of xterm over the past 20 years, we
>=20
> Is the xterm color support due to the capability of running Emacs in term=
inal mode?
>=20
> >   * incorporated ANSI (8) colors,
> >
> >   * adapted the aixterm feature (16) colors,
> >
> >   * added extensions for 88- and 256-colors.
> >   [...]
> >   The 256-color extension came first. 88-colors (using the same control
> >   sequence) came next, to reduce the amount of memory needed. XTerm
> >   stores both foreground and background color indexes for each cell on
> >   the screen. That is two bytes, which doubled the amount of memory use=
d
> >   by xterm for the scrollback. More important, however, was the number
> >   of entries in the colormap. With 256 colors, 65536 entries might be
> >   used, but 88 colors use at most 7744 entries. In the late 1990s,
> >   inexpensive displays were far less capable, requiring workarounds to
> >   get acceptable performance.
> >
> > Steve Berman

Is there some reason why (min-colors 8) does not include the=20
(background dark) and (background light) distinction?