Symbol 5172 from IEC 60417 - Title/Meaning: Class II equipment Function/description: To identify equipment meeting the safety requirements specified for Class II equipment according to IEC 61140.
Additional information: 
The position of the double-square symbol shall be such that it is obvious that the symbol is part of the technical information and can in no way be confused with the manufacturer's name or other identifications
Published in: Supplement B, 1975;2002-10-07
Own work using: iso.org/obp/graphics/grs/3cf63602-6753-4692-9dcb-d746c8b15b10 200.png
Vectorization:  Mrmw