
 
   2) If the reference frame `ref' is not a recognized reference 
      frame the error SPICE(UNKNOWNFRAME) is signaled. 
 
   3) If the loaded kernels provide insufficient data to  
      compute the requested position vector, the deficiency will 
      be diagnosed by a routine in the call tree of this routine. 
 
   4) If an error occurs while reading an SPK or other kernel file, 
      the error  will be diagnosed by a routine in the call tree  
      of this routine. 
 </PRE>
<h4><a name="Files">Fil