Thanks for this clarification, tbone. So there's no Cfg.sort = false as there is with dialogues, and it's back to numbered lines, which are only a pain if you forget things, which I keep doing. Actually, you can leave gaps in the numbering.
Interesting, I've just hit the wretched MyString.split (",") problem, whose details StackOverflow explained to me after I had become totally confused about what a script was doing. You'd think that coding would be like Pure Mathematics, but in fact it's much more like Chemistry, with endless exceptions and special cases and forbidden moves every time you turn around.