Thanks again. That’s really good to know. When I was poking around in the Program Files (x86) folders, I also found the templates for the html files. As these are chock full of html validation errors, I can fix them there and keep a backup somewhere for when they get clobbered during an upgrade.
I didn’t realise that any of the Parchment stuff was in the Inform 7 documentation. I guess I should have a browse through it one of these days.