:'''<nowiki>#</nowiki>''' - '''Information not available'''.:'''u''' - '''Unknown'''. Used when codes are being assigned, but the appropriate specific value cannot be determined.:'''x''' - '''Not applicableapplica'ble'''. Used when a characteristic is not appropriate for the type of entity being described.:'''y''' - '''Not present''. Used when the characteristic being coded is not present for the entity being described.:'''z''' - '''Other'''. Used when codes are being assigned and the characteristics of the entity are known, but none of the defined codes is appropriate.:'''|''' - '''Fill character'''. Used when no attempt is being made to assign the codes.