Re: [TUHS] Any reason the removal/renaming of read-only registers should be permitted?

[Frederic Chartier]

On 2023-05-03 09:29 -0500, G. Branden Robinson wrote:
> At 2023-05-03T09:07:03-0400, Douglas McIlroy wrote:
>
> > rationale for allowing removal of read-only registers
> > [includes :]
> >
> > It simplifies documentation
> 
> This, I would quibble with.  I feel morally compelled to document this
> as one of many differences from AT&T troff.  On the bright side, in
> groff documentation, those considerations are for the most part confined
> to dedicated sections that the newcomer or other user without mastery of
> the AT&T troff dialect easily can pass over.  (And a good thing, as
> those portions of the documentation have grown measurably since I
> started contributing, mainly to document differences that have been in
> place for many years.[1])
> 
> > and relieves a burden on users' understanding.
> 
> True, except for the grumbling grognards we're familiar with who fixed
> their understanding in place many years ago and resist developing it.

Douglas's argument puzzles me. From ksh(1) :

    Unsetting LINENO, MAILCHECK, [...] removes their special
    meaning even if they are subsequently assigned to.

Is the above easier to write or understand than

    It is an error to attempt to unset LINENO, MAILCHECK, [...].

If anything, I would say the opposite. There may be very good
reasons to change or not change the behaviour but documentation
isn't one in my view.