Capacity · The buffer · Element
The usage
How often the buffer was needed.
The part
What it is
Recorded so that the buffer can be sized from experience rather than from intuition.
A buffer used every month is too small; one never used in a year may be too large, though the cost of that is low.
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.