bug#68375: 29.1; lispref documentation fixes

[Stephen Berman]

On Thu, 11 Jan 2024 22:56:42 -0500 Richard Stallman <rms@gnu.org> wrote:

> [[[ To any NSA and FBI agents reading my email: please consider    ]]]
> [[[ whether defending the US Constitution against all enemies,     ]]]
> [[[ foreign or domestic, requires you to follow Snowden's example. ]]]
>
>   >  therefore displayed, at some time, in a window (@pxref{Windows}).  But
>   > -a buffer need not be displayed in any window.  Each buffer has a
>   > +a buffer needs not be displayed in any window.  Each buffer has a
>
> Actually, the old text is more correct English usage.
> "Need" is a special case, and uses the old subjunctive mood

In this sentence "need" is not in the subjunctive mood but is being used
as a modal verb, like "can", "must", etc.  What's special about "need"
in this usage is that it only occurs in so-called polarity contexts
(e.g. negative, interrogative), unlike the ordinary modal verbs (so
e.g. "A buffer need be displayed" is ungrammatical but "A buffer
can/must/may be displayed" is fine).  (An example of the subjunctive
mood is "be" in e.g. "This requires that a buffer not be displayed in
any window."  I can't off the top of my head think of an acceptable use
of "need" in the subjunctive, but perhaps there are such uses.)

Steve Berman