Symbol 6187 from IEC 60417 - Title/Meaning: Continuous operation 
Function/description: To indicate that the laser equipment is set to a mode, where the exposure duration is limited by the operator actuating and releasing the footswitch.
Own work using: iso.org/obp/graphics/grs/7ae14221-d2c6-4ed2-b248-62a793a06285 200.png
Vectorization:  Mrmw