Symbol 2010 from ISO 7000 - Title/Meaning: Level 2 lock Function/description: To identify the control to sustain the level 2 state in the current active group.
Additional information: 
The meaning of this graphical symbol depends upon its orientation.
Own work using: iso.org/obp/graphics/grs/c1bb272a-dfaa-4c5a-bf95-d75c7cee0b7f 200.png
Vectorization:  Mrmw