By default, any user-created ruleset is derived from a master ruleset, which includes the basic heuristic rules to cover the common tasks required by the extraction algorithm. However, it is [yet / still / also]? possible to override each rule in a derived ruleset.
When you want to say another option still exits, what is common? yet or still or also?
However, in my sentence, I think I should use "also" because I am saying that a user is not required to be bound to the rules in the master ruleset?!