Users have the option to change the default constraint values available for a session using the SET SESSION CONSTRAINT statement.
Based on Example: Loading Tables without User OVERRIDE Privileges, U1 might reset the session default Countries constraint:
SET SESSION CONSTRAINT = Countries (UK, Canada);
The session constraint value is changed from the ‘E0’xb to '60'xb (hex representation of 01100000). Subsequent inserts during the session default to '60'xb for the Countries constraint column.