2204.4 (A) Variants for the ¬© Symbol
A variant of the symbol ¬© is acceptable only if it resembles the ¬© closely enough to indicate clearly that the variant is intended to be the copyright symbol. Acceptable variants include:
• The letter c with a parenthesis over the top.
• The letter c with a parenthesis under the bottom.
• The letter c with an unenclosed circle around it.
Examples of unacceptable variants on the ¬© symbol include the following:
• @ (i.e., the letter a in a circle).
• The letter c with a circle attached to the bottom of the letter.
• The letter c in a square.