Automate -- thanks for that; I hadn't come across that tag (and I can't immediately see where it's documented).  I'll give it a try, but I've sort of got used to using underscores.  I started using underscores because a moderator suggested it -- so he obviously didn't know about this tag either!
Somewhere someone else talked of using a full stop where I would use an underscore, and then colouring it white so it couldn't be seen.  Would look better but maybe far too much trouble.