Continuity of state · The visibility · Element
The usage
Whether it is actually used.
The part
What it is
Asked or observed. Agents can say whether they look at it, and observation shows whether they do during a live interaction.
Low usage of available context is a design finding rather than a compliance one.
The smallest level
The attributes it carries
Each attribute is one of the framework’s shared types. What a date is, and how it is written, is defined once for the whole model — the note here says what it means in this particular place.