The window · The opening · Element
The visibility
Who else can see it.
The part
What it is
A regulatory change is visible to everyone; an incumbent’s internal difficulty may be visible to few.
Windows visible to everyone close faster, because everyone responds.
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.