How do I practice containment reference?

The most direct way to practice containment reference is through a focused exercise: Open a current project document or note. Identify three pieces of information that are contained (they live inside this artifact and nowhere else) and three that are referenced (they point to something that exists independently). For each contained item, ask: should this actually be a reference to a shared source? For each reference, ask: is the linked content critical enough that I should contain a summary here? Make one change in each direction.

Common pitfall: Containing everything produces bloated, unmaintainable artifacts — the 200-page requirements document nobody reads because updating one section means re-reviewing the whole thing. Referencing everything produces hollow shells — the project plan that's nothing but links, requiring six clicks to understand a single decision. Both failures come from applying one strategy uniformly instead of choosing deliberately at each node.

This practice connects to Phase 14 (Hierarchy and Nesting) — building it as a repeatable habit compounds over time.