Buffers · The reserve · Element
The size
How much time is held.
The part
What it is
Derived from the ratio and the length of the work rather than chosen. A twelve-week piece of work at a ratio of 1.4 needs around five weeks.
Stated in the plan rather than concealed, which is what makes it defensible.
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.