The sources · The maintenance · Element
The drift
How far the source has moved from reality.
The part
What it is
Checked by sampling against something external. Manual sources drift steadily and the drift is invisible without a check.
The drift rate tells you how often the check needs running.
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.