bug#35885: 25.2; Few mistakes in Emacs Manual (+ proposals)

[Sebastian Urban]

> When N is negative, -N is positive, so the original text sounds
> correct to me.

Of course this way it's correct, but as you wrote few mails before
"This is a user manual, not a mathematical paper (...)" and this
(-1) x (-N) seems like unnecessary burden.  And without it
expressions like "... leaving -N spaces..." or (look below) "mark the
previous −N files" makes no sense.  Readers will more likely to
interpret this '-' as negation of "previous" word.  Just like D. Adams
wrote "(...) it's not obvious - it's easy to misread it.  Of course,
it's not possible to leave a negative number of spaces (...).
A careful reader will figure it out, but that might mean having to
read it more than once."

I was curious how it looks in other examples where 'N' is present,
here is the list:

1. In INFO @ 11.2 Commands to Mark Textual Objects:
A negative argument moves the mark back by N words.

2. In INFO @ 12.1.2 Killing by Lines:
With a negative argument −N, it kills N lines preceding the current
line, together with the text on the current line before point.

3. In INFO @ 14.2 Recentering:
A negative argument -N puts point N lines from the bottom of the
window.

4. In INFO @ 25.2 Sentences
... with a negative argument −N, it kills back to the beginning of the
Nth preceding sentence.

5. In INFO @ 26.2.2 Moving by Defuns:
‘C-M-a’ with a negative argument −N moves forward N times to the next
beginning of a defun.

6. In INFO @ 26.5.1 Comment Commands:
A positive argument N adds N delimiters, while a negative argument -N
removes N delimiters.
...
With a positive prefix argument N, it operates on N lines starting
with the current one; with a negative N, it affects N preceding lines.

7. In INFO @ 30.6 Dired Marks vs. Flags :
[at '* m']... (if N is negative, mark the previous −N files)...
...
[at '* u']... (if N is negative, unmark the previous −N files)...
...
[at '* <DEL>']... (if N is negative, unmark the next −N files)...

8. In INFO @ 30.7 Operating on Files:
(If N is negative, the command operates on the −N files preceding the
current line.)

--- end of examples ---

So, in 2., 3., 4., 5., 6.(1st), we have pattern of "negative argument
-N ... something N something..."

In 1. it's something similar but without '-N' just "negative
argument", also 6.(2nd) is something similar but 'N' doesn't have
minus sign.

But in 7. and 8. (and the one I already sent) we have "if N is
negative... something -N something".

So, after looking at more examples, I think the best idea would be to
go with the most used pattern, therefore:
   - add '-N' to 1.,
   - add minus sign do 6.(2nd),
   - replace - in 7., 8., and the one I sent - "if N is negative"
     with "with negative argument -N" then change '-N' to 'N' in the
     rest of each sentence.

There is also a problem of minus sign, or to simply put - lack of it
in 3. and 6.(1st) and the one I sent - there we can see "hyphen-minus"
(#x2d).  In other cases it is "minus sign" (#x2212).

If we agree on this I could send message with "In FILENAME.TEXI
L?-? change this line to this" if it helps you (I don't know how
to make normal patches, sorry).