To allow for compatibility with RDBMS systems that do not support sequences, this table may be used to store the last used WID. MySQL dataset loaders use the following SQL for WID assignment: DELETE FROM WIDTable; INSERT INTO WIDTable VALUES (); SELECT last_insert_id(); It may also be used in RDBMS systems that do not support auto-increment of a counter; however additional protocol like table locking may be needed to assure the integrity of WIDs during concurrent assignment. This table contains exactly one row at any given time.