You need to convert a string to all uppercase or all lowercase.
Use httpd_util:to_upper or httpd_util:to_lower from the OTP httpd_util module. (Yes, I know that these would make more sense in the string module!)
1> httpd_utils:to_upper("hello"). "HELLO" 2> httpd_utils:to_lower("ERLANG"). "erlang"
The httpd_util module contains a dog's breakfast of functionality that probably belong in other modules, but that have not been added due to backwards-compatibility concerns.