In the IIDC specification, the Exposure feature provides auto exposure similar to a "contrast control".  Pixelink cameras do not support this feature.  The same functionality is provided by the auto control of the shutter feature.  To prevent confusion and ease software development, FEATURE_EXPOSURE has been aliased to FEATURE_SHUTTER in software API release 6.21 and later.

Please see the Shutter feature for more information.