What is Accessory Obligation?

Legal Definition
In the civil law. An obligation which is incident to another or principal obligation; the obligation of a surety. Poth. Obi. pt. 2, c. 1, § 6w In Scotch law. Obligations to antecedent or primary obligations, such as obligations to pay interest, etc. Ersk. Inst lib. 3, tit 3, § 60.
-- Black's Law Dictionary