Symbol 6081 from IEC 60417 - Title/Meaning: Function key Function/description: To identify the control to invoke a function or a graphic character selected by another simultaneously invoked key, defined by the hardware manufacturer, in general implemented independently of software.
Additional information: 
See considerations about this function in ISO/IEC TR 15440 and in ISO/IEC 24757.
The frame shown here around the letters ""Fn"" is optional.
Own work using: iso.org/obp/graphics/grs/7475b810-0eb0-4e5e-890f-b6acf44d79d7 200.png
Vectorization:  Mrmw