It's bad wording. If you use special characters...you don't have to...pick 'em from the list of specific special characters. Special characters just make a password stronger. If you tried using 2 special characters, were they the same special character or the same special character repeated?
"Any form" wouldn't include all permutations of a previous password, user ID or account. It just can't be the same or obviously close to any credential, such as being backwards or different case. If you previously used "dump," you probably couldn't use "damp." I'm sure "mudp" would be okay.