When the javax.jdo.option.Optimistic option is enabled, or optimistic locking is otherwise turned on, Kodo will utilize the value of the lock-column metadata extension (which default to JDOLOCKX) to determine which column to use for its "lock column". The lock column holds an interger which is incremented each time changes are committed to the object, and is utilizied to determine whether an optimistic transaction should succeed or fail.