Emergency escape 
In an emergency, it must be possible to unlock the escape release from the hazard area/from the machine side without any additional equipment. The device must be manually operated and it is essential that it acts on the barrier. Activating the release must lead to a permanent locking of the guard lock (see also mechanical release).

Emergency unlocking/locking 
The emergency unlocking is designed to unlock a guard lock in an emergency. The unlocking can be carried out from the access side/outside without any tools. During emergency unlocking, the switch engages in the unlocked position and a procedure similar to a repair will be required be reset to its original position.

Safety Integrity Level (SIL)  
Safety Integrity Level is the level that describes the probability that a safety-related system will perform the required safety functions as required under all specified conditions within a specified period of time. When assessing this, the Safety Integrity Level to be achieved is compared (SILr; the "r" stands for "required") with the "actual" SIL that has been achieved.

Mechanical release Emergency unlocking/locking 
If a guard locking device fails, it can be unlocked from the access side/outside by means of an auxiliary release. Unlocking is done with a tool or a key. The mechanical release should be protected against misuse (seal, varnish).

Performance Level (PL) 
A discrete level that specifies the ability of safety-related parts of a control system to perform a safety function under predictable conditions (as defined in the DIN EN ISO 13849 standard). Simply put, the performance level is a measure of the reliability of a safety function. A distinction is made between the performance level to be achieved (PLr; the "r" stands for "required") and the "actual" PL that has in fact been achieved. There are five performance levels that represent different residual risks.