I do hope it is OK for me to post this as a separate question, if it is wrong please say so.
I received an excellent answer from Carsten S to my question of why the dative was used in the second clause in this sentence:
Tipps für den Besuch in Schwäbisch Gmünd - einer süddeutschen Kleinstadt.
Carlston said that the case of einer süddeutschen Kleinstadt is the same as that of Schwäbisch Gmünd, it is just that for the name you cannot tell as clearly that it is dative.
I understand that, but what if the "-" were a ","? Would the second clause still be in the dative? I guess what I am asking is this: If an object is dative in the main clause, is it always also dative in the second clause?