NAME:
  calibchg
 PURPOSE:
  Calibration structure maintenance utility.
 DESCRIPTION:

 CATEGORY:
  CCD data processing
 CALLING SEQUENCE:
  calibchg,calib,item,subitem,CALIBPATH=calibpath
 INPUTS:
  calib - Input calibration structure (note this precise
 OPTIONAL INPUT PARAMETERS:

 KEYWORD INPUT PARAMETERS:

 OUTPUTS:

 KEYWORD OUTPUT PARAMETERS:

 COMMON BLOCKS:

 SIDE EFFECTS:

 RESTRICTIONS:

 PROCEDURE:

 MODIFICATION HISTORY:
  99/06/05, Written by Marc W. Buie, Lowell Observatory
  99/11/15 - MWB, fixed bug for case of adding a filter to an empty flat list.