Spanning isogeny classes of principally polarized abelian surfaces with RM

We describe how isogenies between principally polarized abelian surfaces (PPAS) with real multiplication (RM) can be decomposed into elementary isogeny types. This leads to a strategy for enumerating the isogeny class of a given PPAS with RM. This note is part of an ongoing work with R. van Bommel, S. Chidambaram, and E. Costa and is not indended for separate publication.