enclosed alphanumerics
Special characters:
Enclosed C
Enclosed A
Copyright symbol
Registered trademark symbol
Sound recording copyright symbol
At sign
(partially enclosed A)
Character sets:
Japanese rebus monogram
Enclosed Alphanumeric Supplement
Enclosed CJK Letters and Months
(extends enclosed Arabic decimal numbers to ㊿)
https://en.wikipedia.org/wiki/Enclosed_Alphanumerics