Database conditions allow alternate paths of control depending on the
  truth value of a test involving conditions peculiar to the database
  environment.  The database conditions are the tenancy, member, and
  database key conditions.

  The member condition determines whether member records are present
  in one or more sets.  Only member record types defined in the
  Sub-Schema Section are considered in determining the truth value of
  the condition.

  Format -

   [ set-name IS ]   [ NOT ]   EMPTY

  set-name is a subschema set name.