What does “locked out, do not remove” mean?

In the LOTO (Lockout-Tagout) field, there is a set of seemingly simple but extremely important statements – “Lock it, do not remove it.” 
It is not just a slogan; rather, it is the hardware standard set by OSHA (the United States Occupational Safety and Health Administration) and China’s GB/T 33579-2017. These six words address a fundamental question: When a lock is attached to an energy isolation device, to what extent does it need to be “locked” to be considered qualified? 
The answer is straightforward: It must be so sturdy that no one can remove it without using force. In other words, if someone can dismantle your lock with their bare hands or with common tools at hand, then the lock is not up to standard – it has not achieved the “locked, cannot be removed” requirement. 
The provisions for protective materials and hardware as stipulated in Section 6.3.2 of the Chinese standard GB/T 33579-2017: 
Each lockout device and tagout device should be uniquely identified. They should only be the sole devices used to control hazardous energy and must not be used for any other purposes. They must also meet the following requirements: 
c) The locking devices and tagging devices (including their accessories) should be sufficiently sturdy to prevent them from being removed inadvertently or accidentally without the need for forceful or destructive methods. 
Key finding: The two standards are highly consistent in their “durability” requirements – the device must be so sturdy that it cannot be easily removed by ordinary people. It can only be removed through violent means (such as with wire cutters) or by the person applying the force using a key. 
“The lock should be durable and its design should ensure that removal by abnormal means requires extraordinary force or techniques. Moreover, the lock should have the capability of being controlled by individual keys or combination keys.” 
Compliance determination criteria: If a lock can be removed by hand or with common portable tools (screwdrivers, pliers, wrenches) without significant effort, it does not meet the “durability” requirement.

Compliance determination criteria: The key must be exclusively controlled by the user. Any design or method that enables a second person to open the lock without using force does not meet the “non-removable” requirement. 
Compliance determination criteria: Apart from the person applying the lock and the legal emergency removal procedure, no one is allowed to remove the lock of another person. The “unremovable” at the program level ensures that even if the lock can be physically damaged, it is not permitted to be removed at will.