This chapter is for people changing pylcm itself. Public model semantics and numerical
methods live elsewhere; private _lcm representations and contributor workflows live
here.
A solver can be written against the public names alone, and Custom solvers is the guide to what one owes the engine. That page defines the exact-version persistence, replay, and conformance contract, which is why it, rather than these implementation notes, is the reference for an out-of-tree author.