Scope is the tangible outcome of project tasks

I think he considers scope to be a true sibling of cost and schedule, not above or below

Scope is not value or work but the basis of value and the result of work

This makes me think

Scope is the mapping from work to value

Scope attributes

Units: drawings, parts, etc

Effort: nominal hours, story points

Divisibility

Complexity, uncertainty

Target neutral

If customer target changes then value of scope changes but the scope is not changes

Resource Nominal

eg

Man months

Exception realistic

A way to describe a scope partial, imperfect, and rework