So pretty much a free choice, except for maybe a few jurisdictions where a local code applies. Thanks.
A point for you to ponder though: Now that electrical and building codes are moving toward "international" versions, do you see symbolic signs eventually replacing simple "EXIT" signs in America?
Exit signs which incorporate a pictogram are now required here in England, either with or without wording:
More signs here. [This message has been edited by pauluk (edited 01-18-2004).]