Symbol 1973 from ISO 7000 - Title/Meaning: Constant recall 
Function/description: To identify the control on the display for a constant recall, for example on office equipment.
Own work using: iso.org/obp/graphics/grs/7b6da8bb-afdf-4424-a0f5-bb33e9f7db79 200.png
Vectorization:  Mrmw