The drive can have multiple "adapters" which can each be allowed or disallowed from having certain control options by using the masks.
Usually, the least significant bit is the terminal strip, and the next one might be the built in HIM, and then might be the build in scanport, next bit could be an add-on comm card, etc.
Is your drive a 1336 Plus, or Plus II? I have found manuals for the Plus II and found that 90% applies to the Plus also.