The “container_lockable” type is defined in CoreTypes.aslx. It implements locking and unlocking functionality. It does not inherit any other container types, so one of container_open, container_closed or container_limited should also be inherited.
By inheriting the “container_lockable” type in an object, script is added to the open and close attributes to implement the check to see whether the object is locked before allowing open/close. The “lock” and “unlock” verbs are added to the object. The container is locked by default, and the autoopen and autounlock attributes are set to “true”.