Dear Peter, Bruce Bartlett forwarded me your email. I'm reasonably convinced that there is no difference of meaning, when you use the accent. Accents are often used on words borrowed from another language: the story is broadly similar that of the word "cafe". For some reason, the accent is commoner for "cafe" than for "role" (but still apparently optional, in practice). If there's any nuance or distinction at all, then it is one of pretension. So an upmarket, traditional establishment would definitely be a caf\'e, but a downmarket one is more likely to be a cafe. So it is, perhaps, with "role": I know working mathematicians who prefer accenting it purely because it seems grander. My regards to Toby Kenney, if you see him around. Cheers, James Cranch