In , Paul Hyett
spake thusly:

BTW, a follow-up : I'd like the cell fill colour changing only
if it wasn't empty. Presumably the 'ISBLANK' function would be
involved somehow?

Not a direct answer to your question, which I believe has been
answered at any rate -- but I coincidentally just finished working
out a reusable module to handle some Conditional Formatting functions.
It's working out to be rather nifty for me, so I've made a web page
about it and am happy to give away the code.

http://heliotropos.com/xl/code/cfmagic.html

=dman=