Symbol 6339-3 from IEC 60417 - Title/Meaning: Finger/hand placement, thumb of right hand Function/description: To indicate that the system requests the thumb of the right hand to be placed on the platen.[]A mirrored graphical symbol may be used to indicate that the system requests the thumb of the left hand to be placed on the platen.
Additional information: 
The meaning of this graphical symbol depends on its orientation.
See also IEC 60417-6339-1, IEC 60417-6339-2, IEC 60417-6340-1 and IEC 60417-6340-2.
Own work using: iso.org/obp/graphics/grs/f0ccd43d-3853-4a7e-97b7-1bbc9d5eb557 200.png
Vectorization:  Mrmw