Removed FOCAL_PLANE_Z_DIRECTION keyword

           "description": "The type of interpolation method to use.",

           "type": "string"

       },

       "FOCAL_PLANE_Z_DIRECTION" : {

           "description" : "The z-direction of the focal plane. FIXME can we make the ISD-creator deal with this?",

	   "type": "number"

       }

   },

   "required": ["FOCAL_LENGTH", "BORESIGHT","CCD_CENTER","IMAGE_LINES","IMAGE_SAMPLES", "FOCAL_PLANE_Z_DIRECTION"]

}