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
