Re: End-of-sentence spacing

[Peter Schaffter]

On Tue, Dec 22, 2020, Dave Kemper wrote:
> It seemed a minor thing before, but now that it's tripped up the
> author of possibly the most elaborate macro package published in
> the roff language's 50-year history, I wonder if that's worth
> revisiting.

Being said author, I can confirm that yes, I did indeed get tripped
up in exactly the way Dave described: quick check of paragraph one
to refresh my memory, not reading under the fold, forgetting that
sentence space means additional space.  I obviously knew once or mom
wouldn't have macros for manipulating word and sentence spacing,
but it's something I haven't had to think about in years.

That said, while the info entry for .ss is accurate as is, the
material does need to be re-ordered somewhat.  First off, a reader
of the entry, looking for information on sentence spacing, and
rationally assuming 'ss' stands for 'sentence space,' is presented,
surprisingly, with "Change the size of a space between *words.*"

Then, because of the capitalization of the argument descriptions,
the eye tends to jump to: "Initially both the WORD_SPACE_SIZE
and SENTENCE_SPACE_SIZE are 12," which, without some explanation
of sentence space, leads to the conclusion that the value of
sentence_space_size is discrete.  The erroneous conclusion
then appears to be confirmed in the second paragraph:  "If the
second argument is not given, sentence space size is set to
WORD_SPACE_SIZE," which, as before, suggests "is equal to," not
"is added to", word space size.

So, yes, it's worth re-working the info .ss entry.  Perhaps begin
with something like: "Change the size of the space between words
and sentences.  The space between sentences is derived by adding
WORD_SPACE_SIZE and SENTENCE_SPACE_SIZE.  Thus '.ss 12 0' results in
no additional space being added between sentences, whereas '.ss 12 12'
results in an additional 12 units of space between sentences."

-- 
Peter Schaffter
https://www.schaffter.ca