Production · The capacity · Element
The ceiling
What the plan may not exceed.
The part
What it is
Throughput minus buffer, stated as a number and owned by someone. Without an owner the ceiling is advisory, and an advisory ceiling is not one.
It should be revisited when the workflow changes, and not otherwise. A ceiling renegotiated every planning round is a wish.
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.