PL = perl, maybe. Quoting Larry Wall: (A little context first. The topic was "Perl, the first postmodern computer language," which explains the reference to W

PL = perl, maybe. Quoting Larry Wall: (A little context first. The topic was "Perl, the first postmodern computer language," which explains the reference to Windows still being "Modern age" and bringing up "pm" as an extension. He mentioned "D" as a possible name of a successor to "C" but it didn't exist yet. "D" did show up 2 years later though.) > Okay, let’s see. "pm" is an abbreviation for Perl Module, which is why, of course, we use ".pm" is the extension for a Perl module. It used to be that we used ".pl" for Perl code. People still do use ".pl" in Windows, but that’s because they’re all still stuck back in the Modern age. Anyway, there’s a funny thing about using ".pl" for the Perl extension. People used to argue a lot about what the next language after C would be. Everone knew that the previous language had been called "B", after the first letter in BCPL, which came even earlier than B. The two proposed candidates for the next language were "D", because that’s what comes after "C" in the alphabet, and "P", because that was the next letter in BCPL. > Well, as you can see, it didn’t work out either way. One of the successors to C was C++, which is a cute pun on the autoincrement operator, but makes it an absolute pain to try to figure out what the proper extension for a C++ file should be. .C? .cpp? .cxx? I suppose as a postmodern person, I shouldn’t mind the diversity, but somehow I do. I suppose a little inconsistency is good for the soul. > Anyway, the other successor to C gobbled up two letters instead of one. Which is why many Perl scripts have the extension, ".pl", finishing off BCPL. It’s a pity, in a way. Now there can never be a language named "L". Perhaps it’s just as well. Quite apart from the annual yuletide puns we’d get on "noel, noel", there’s also the problem that people would have confused the language with lex, which already uses a ".l" extension. Since lex had already taken it, noel was available. So to speak. Sorry. https://www.perl.com/pub/1999/03/pm.html/ https://www.perl.com/pub/1999/03/pm.html/