Here, you can create, update or delete Global Parameters.
Global Parameter is a name/value pair. Once defined, you can use the name in a directive parameter field and it will be replaced in the final rule by the value for that name.
The syntax to call a parameter is ${rudder.param.name}, where name is the chosen name for you Global Parameter.
Be careful to exactly use (lower case) rudder.param and your parameter name with the same case (Global Parameter name are case sensitive).