Using The System Lock Key - Lenovo ThinkPad T520 User Manual

Using the system lock key

The system lock key has two positions, unlocked and locked.
When the key is in the locked position, the eject button of the ThinkPad Mini Dock Series 3, the ThinkPad
Mini Dock Plus Series 3, or the ThinkPad Mini Dock Plus Series 3 (170 W) is locked, and you cannot remove
your computer. The key lock indicator lights when the eject button is locked.
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