Usually, it is the path of egress and it would also include lighting outside of the exterior doors.
I can't find my antique copy of NFPA 101 but it might not be the code being enforced. You should ask your AHJ which code this requirement comes from. Most inspectors will also be willing to tell you what the specific requirements are.
Generally, from what little I know on the subject, the path of egress must be illuminated to 1fc average with no point being less than .1fc Most manufacturers or their agencies would be willing to do this layout for you. Some catalogs show specific spacings & mounting heights to achieve the 1fc.
[This message has been edited by Tom (edited 05-13-2006).]
Few things are harder to put up with than the annoyance of a good example.