Symbol 6072-13 from IEC 60417 - Title/Meaning: Space, select Function/description: To indicate a space or a spacing function selected by a subsequently invoked key (e.g. by latching to a group containing different spaces).
Additional information: 
The graphical appearance of the outer graphical symbol element is an application of ISO 7000-2015.
Own work using: iso.org/obp/graphics/grs/3983e256-e654-4c83-935b-01d9343bd3c3 200.png
Vectorization:  Mrmw