We had a discussion in a thread started in 11-06-2001 by GWRoss about if…then…else.
http://www.chiefdelphi.com/forums/showthread.php?threadid=1021&referrerid=147
Do you suppose Parallax reads Chief Delphi ? 
Hmmm… it’s a good possibility, since Innovation First, and through them, FIRST, is a large user of PBASIC.
In terms of the number of people who use Stamps, FIRST/InnovationFirst is a very small percentage. My guess is that people in the Parallax Yahoo! group asked for it as they have much more influence over Parallax than we do.
Also, if Parallax wants to remain competitive with C-based processors, they need to keep their language at least somewhat user-friendly. Let’s face it: if NOT is not a user friendly construct.
InnovationFirst may have asked Parallax about it, but I would doubt if Parallax got the idea from reading ChiefDelphi. Besides, that thread is over a year old. At that point, neither FIRST nor ChiefDelphi were anywhere near the size they are now.