What is a mandatory cross-claim in small claims court?

Upon the commencement of a small claims action by a plaintiff, the defendant "may file a claim in the same proceeding" ( 116.8, subd. (a)) but need not do so to preserve the claim. Stated otherwise, there is no such thing as a mandatory cross-claim in small claims court. (Davis v. Superior Court (1980) 102 Cal.App.3d 164, 170, 162 Cal.Rptr. 167.) If the defendant does file a claim in the same proceeding, the parties' rights to appeal are equal: "The defendant with respect to the plaintiff's claim, or the plaintiff with respect to a claim of defendant, may appeal the judgment to the superior court...." ( 117.8, subd. (b), as amended by Stats.1989, ch. 1416, 6.) ²