Dead locking latch bolt operated by knob/lever from either side except when outside knob/lever is locked by the push or turn button inside. Key outside or operating inside knob/lever releases push or turn button unlocking outside knob/ lever except when push or turn button has been rotated to keep outside knob/lever locked. Inside push or turn button must be manually operated to unlock outside knob/lever. Inside knob/lever always operates latch bolt.
