Re: weird \s

[Doug McIlroy]

Thanks for spotting the facts in info, a jungle I rarely
enter. Especially for groff, for which groff(7) is quite a
comprehensive reference.

The difference between \s39 and \s40 is a documented living
fossil!

Clearly this dates from the first CAT phototypesetter's limited
range of point sizes: 6 to 36.  In one of his less brilliant
moments, Joe Ossanna apparently built that limitation into
troff's tokenizer: \s ate one digit, or two if the second is
not more than 3. This was not spelled out in the Troff User's
Manual, nor did it apply to .ps.  Hidden away as it was, the
obsolete feature persisted past the arrival of more capable
typesetters.

Did the author of groff steal the code from Bell Labs?  Or did
he merely read the code and preserve the feature in a misguided
nod to backward compatibility?  Did he find it by experiment?

Doug