The following CREATE CONSTRAINT request defines values and enforcements for a hierarchical (level) classification system, within which the values are hierarchically related.
CREATE CONSTRAINT classification_level SMALLINT, NOT NULL, VALUES (top_secret:4, secret:3, confidential:2, unclassified:1), INSERT SYSLIB.insert_level, UPDATE SYSLIB.update_level, DELETE SYSLIB.delete_level, SELECT SYSLIB.read_level;