Symbol 6265 from IEC 60417 - Title/Meaning: Position of use, horizontal Function/description: To indicate that the instrument to be used with the dial horizontal.
Additional information: 
See also symbol IEC 60417-6264 and IEC 60417-6266.
IEC 60051-1 provides technical details.
Own work using: iso.org/obp/graphics/grs/181e08de-fd5d-4169-9bbb-c40d8b14a09d 200.png
Vectorization:  Mrmw