The economics · The liability · Element
The breakage
How much is assumed never to be redeemed.
The part
What it is
Estimated from historical behaviour rather than assumed. The estimate materially changes the liability and therefore the reported profitability.
A programme that only works at high breakage is fragile, since expiry rules and consumer protection have both been tightening.
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.