The limits · The exclusions · Element
The pressure
Where the limits are being pushed.
The part
What it is
A new capability, a performance target or a competitor doing something. Each produces a reasonable-sounding case for one exception.
Recording the pressure makes the eventual erosion visible rather than gradual.
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.