Under the hoodTier: how much it should matter to you
1Useful: my rating, 1 to 5
3Signal: worth watching, 1 to 5
ModelsArea: what it touches
In DevelopmentKind: in v2.1.248,
In DevelopmentSection of the release
A new list, not a new family; selectability is not settled here.
What
A list used near model validation now names three families: fable, opus and sonnet. The fable family already existed in the previous build, so this is a new list rather than a new family, and whether it is selectable is not settled by this code.
Evidence
var S = ["fable", "opus", "sonnet"];
Strings lifted out of the shipped bundle, so the claim above can be checked against them.