Margin structure · The scale model · Element
The cost split
Which costs are fixed, which vary with volume, and which do neither.
The part
What it is
Costs described as fixed are often fixed only within a range. Outside it they step, which is a different behaviour requiring a different plan.
The split is what determines whether growth is worth pursuing at the current price, which is the underlying question.
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.
Cost behaviour
Fixed, variable or stepped — the third is the one that breaks forecasts.
Choice shared type