In order: the authored name; the first non-displayed categorical
dimension (a labelled axis is an author saying "these are named states");
then the first non-displayed discrete one small enough to be a menu. Spatial
and displayed axes are never candidates — those are the scene, not its
chapters.
Which dimension the chapters walk.
In order: the authored name; the first non-displayed categorical dimension (a labelled axis is an author saying "these are named states"); then the first non-displayed discrete one small enough to be a menu. Spatial and displayed axes are never candidates — those are the scene, not its chapters.