True when the values match the meshes and placements as they are now.
What the latest sign data builds found out about the target meshes,
together: closed and consistentOrientation when every target is, the
counts summed, and the first target's mode. See
Scene.fieldTargetStatus for each target.
No boundary or non-manifold edge.
The mode in use (never "auto").
The state of a field, from Scene.fieldStatus.