  mapped to NAIF integer codes, the error SPICE(IDCODENOTFOUND)
      is signaled.
 
   3) If `obsrvr' and `target' map to the same NAIF integer ID codes, the
      error SPICE(BODIESNOTDISTINCT) is signaled.
 
   4) If frame definition data enabling the evaluation of the state
      of the target relative to the observer in the target body-fixed
      frame have not been loaded prior to calling <b>illum_plid_pl02</b>, the
      error will be diagnosed and signaled by a routine in the call
      tree of thi