That's (a) an awfully counterintuitive interface, though I did eventually figure it out, (b) still pretty darned cool, but (c) falls so far short of what I usually need when I have to think more than two seconds about an RE that I wonder whether I've been using the wrong tools for a while and need to finally get around to finding out what lexx and yacc do. (If that RE tool had a button for "the pitch part of a note in ABC syntax" or "a complete ABC note with or without all the optional components", that'd be helpful -- and that can be done with an RE -- but I guess that's really more of a write-a-parser situation than a write-a-RE situation.) I guess the author has done me a service by making it easier for me to see that, even if I'm not the right audience for that particular tool.