Incorrect DXC setting

ERROR
CMPSC incorrectly sets DXC to "Decimal operand" on normal completion (most of the time) or after a specification exception.

INTRODUCED
Error was introduced by Fish on 1 January 2008. His intention was good, but he implemented DXC setting wrong.

REMEDY
DXC is only set on a data exception.

REPORTS
It has never been reported, but recently a (secret) user, reported the error.