The escutcheon lock has a knob or button from the side, if it is twisted or pressed, the privacy mode will be enabled.

If the privacy mode has been engaged, in the website, the site admin can see below icon:

A normal valid user will be rejected, only the user with overwriting privacy mode permission can unlock the lock.

The privacy mode permission can only be enabled by the site owner. Below is an example of the user who has no override privacy mode checked, which means he cannot lock a lock that is in privacy mode.