Graham, this directive should work in TeXShop as well, that's where we got those directives from (In fact, TS is for TeXShop). If I remember correctly though, TeXShop is very picky about spaces or not around the equal sign, I can't remember what it expects but it is picky about it. But it is certainly an "editor" thing, not a "latex" thing, so it's up to each editor to support it or not, TeXShop started it I think. So that would be something to take up with the
Ah, OK I am learning a lot here so I need to check this out on an editor by editor basis.
Thanks again.
Graham