Symbol 6143 from IEC 60417 - Title/Meaning: Overlay, combining short slash Function/description: To identify the key to type the character of combining short slash overlay.
Additional information: 
This symbol corresponds to the hexadecimal code U+0335 named COMBINING SHORT SLASH OVERLAY of the Unicode ISO/IEC 10646-1 when this key is entered by the dead key method.
The outlined rectangle is presented as such, or as a solid rectangle, in a colour different from the colour which otherwise is used for characters on the keyboard (usually a lighter colour or gray shade). In this case, the other parts of the symbol are to be presented in the colour which otherwise is used for characters, obscuring the rectangle where they overlap it.
Own work using: iso.org/obp/graphics/grs/542483cb-aa05-471c-95ba-3619b74ced07 200.png
Vectorization:  Mrmw