Re: master 391ff93f763 3/4: * doc/misc/calc.texi (Musical Notes): Fix build with Texinfo 4.13.

[Eli Zaretskii <eliz@gnu.org>]

> From: Po Lu <luangruo@yahoo.com>
> Cc: emacs-devel@gnu.org,  ruijie@netyu.xyz
> Date: Wed, 09 Aug 2023 20:24:02 +0800
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > Then I guess we are getting to the point where makeinfo 4.13 will no
> > longer be a viable option.  The current makeinfo, though still slower
> > than 4.13, is significantly faster than the original 5.x versions if
> > you build Texinfo with Perl extensions, and has too many useful
> > features to stay with 4.13.  So I urge you to upgrade.
> 
> [...]
> 
> > I don't know, please ask on the Texinfo list.  And meanwhile please
> > revert those changes, they should not have been installed in the first
> > place.
> 
> I would prefer we wait for a need more pressing than @sub before making
> such a decision, because Texinfo 5.0 requires a newer Perl than is
> installed on many of the systems I use.

The current Texinfo version is 7.0.3, not 5.0.

> In fact, @sub is not strictly
> necessary; when the output is Info or ASCII, it emits:
> 
> a midi number to scientific pitch notation.  For example, ‘500 Hz’ gets
> converted to ‘B_4 + 21.3094853649 cents’ and ‘84’ to ‘C_6’.
> 
> which is not very distinct from:
> 
> a midi number to scientific pitch notation.  For example, ‘500 Hz’ gets
> converted to ‘B4 + 21.3094853649 cents’ and ‘84’ to ‘C6’.
> 
> and possibly more confounding, as underscores are seldom seen in musical
> notation.

I'm okay with a change that will remove @sub from @ifinfo text, but
before we go that way, please see what the Texinfo folks have to
offer.