The criteria

The specific conditions that have to hold.

The part

What it is

Good criteria are observable rather than evaluative. “The migration script runs without manual intervention” can be checked; “the migration is going well” cannot.

Three to five conditions is usually enough. A longer list is a sign the milestone is really two.

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.