How a template gets its inputs, composes from other templates and assets, makes output safe, works with lists and uses per-visitor state.
Mechanics are the facts the engine fixes, so these pages state them as facts: what a template receives on every page, how one template renders another, how scripts and images are registered, how output is encoded, what a list is, and how permission-gated personalization works. They come before the recipes in Common Development Patterns and the advice in Development Practices, which assume them.
The pages run in the order a template meets them. The page and its inputs come first, including the request. Then come the two ways to break a page into pieces: Includes for template code and Snippets for markup an editor owns. Assets and Images, Safe Output and Handling Missing Data and Working with Lists follow. Permissions comes before Personalization because every personalization tool works only when the session permission is allowed.