Loyalty · The lock-in · Element
The sources
What holds each customer, other than preference.
The part
What it is
Contractual term, technical integration, data held, process dependency, habit, or simply that nobody has looked.
Most retention is a mixture, and knowing the mixture is what makes the loyalty number interpretable.
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.