No, it's not, the whole classic litany of scrum rituals (“scrume events” in the guide’s language) is prescribed in the Guide.
> Two week increments, for example. I've heard so many people complain about scrum mandating two week increments, when it doesn't actually.
That’s strictly true, but somewhat misleading, as while it doesn't mandate two-week sprints specifically, the guide does specify that sprints are not more than one month. (And that they have “consistent duration throughout a development effort”, which is probably a more problematic command. But the most problematic is using synchronized iterations rather than flow for dev work, and locking the time cycle for product iterations to the time cycle for process improvement.)
> Or people complain about "velocity", and "story points" which are likewise not part of scrum at all
Yeah, they are an attempt (and, used as designed, probable the best attempt yet) to deal with a well-documented hard problem un software development which Scrum just assumes is, and requires to be, solved without really commenting on directly. I have far less complaints about them (except that people cargo cult them badly) than Scrum, which, while also subject to bad cargo-culting, has a lot of it's problems baked into the fundamental spec.