What is "abensberg-traun"

Abensberg und Traun (now usually written Abensperg-Traun) is the name of an Austrian noble family, originally from the Upper Austrian Traungau, and one of the oldest extant aristocratic families in Central Europe. They are one of the so-called "Apostel Houses", i.e. they are one of the few families which had already played a historical role during the period of Babenburg rule of Austria (976 to 1246).