The /DIFFERENCE_MODE qualifier changes the operating mode of CASPIR to a diagnostic mode in which the Current array (or ICurrent array) is automatically copied directly into the Subtract array (or ISubtract array) at the time that it is uploaded to the VAX. Used in conjunction with the /CHANNEL_STATISTICS qualifier, this enables the transputers to generate statistics about the difference between the current frame and the previous frame.
The /NODIFFERENCE_MODE qualifier restores normal operation.