calculating fte for dummies

the LEED NC reference manual doesnt actually seem to have directions anywhere on how to arrive at FTE. It makes reference to it as if its just innate human knowledge we are born with. The appendix has some info for core and shell, but its insufficient and also im left uncertain if it also applies to everything other than core and shell. the conversations below seem to be focused on specific cases. How do we begin to go about this? does the owner/design team have to give us the number of employees that work at any given shift? or is it done by sq ft/occupant load? ad what about visitors ("transients")? im really need to start from the very beginning and do not see any fundamental info anywhere on this. im clearly not aware of some critical document (?).