In the 1996 NEC, 384-13 General, the last sentence read :All panelboard circuits and circuit modification shall be legibly identified as to the purpose or use on a circuit directory located on the face or inside of the panel doors". This sentence does not appear in the 2002 NEC, 408.13 General.
Currently we identify on the receptacle what panelbox and circuit breaker(s) feed the receptacle. Therefore the directory in the panel box is blank. This done because workstations and equipment can be easily re-located and eliminates the constant need to update the directory. Is this practice considered acceptable?
Try looking in 408.4 in the 2002 Code. "All circuits and circuit modifications shall be legibly identified as to purpose or use on a circuit directory located on the face or inside of the panel door in the case of a panelboard, and at each switch on a switchboard."