The characters with case are a subset of the alphabetic characters. A character with case has the property of being either uppercase or lowercase. Every character with case is in one-to-one correspondence with some other character with the opposite case.
184.108.40.206.1 Uppercase Characters
220.127.116.11.2 Lowercase Characters
18.104.22.168.3 Corresponding Characters in the Other Case
22.214.171.124.4 Case of Implementation-Defined Characters