Ownership · The custodian · Element
The role
Who operates the system.
The part
What it is
Usually a technical function, and the distinction from ownership should be written down since it is otherwise assumed one way or the other.
For third-party systems, the custodian is partly external and the boundary matters.
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.