Two issues: 1. In 5.2.1, and "5.2.2 Maintaining and updating the ABI " document "debian/abi/" and "debian/config/defines" - neither of which now exist. This needs updating to reflect how it is done today. 2. The copy published at https://www.debian.org/doc/manuals/debian-kernel-handbook/ch-versions.html is very out-of-date (2018).