Thanks, John. I didn't know where to put it. Seemed beyond where we were at in chapter 2. And I do code this stuff. See https://hillside.net/plop/plop97/Proceedings/haugen.pdf
I'm open to being grilled, but am very slow to read and write the mathematical notation so far (don't have a good math background), so it might be better to wait for your timed petri net explanation and see what it does for me.