Diagnostics: Measure and Subject
Halliday & Matthiessen (2004: 264):
There is no very sharp line separating (circumstantial) expressions of Extent from (participant) expressions of Scope of the enhancing type; but there is a distinction between them: Extent is expressed in terms of some unit of measurement … whereas Scope in terms other than measure units … and being a participant, the Scope has the potential of being able to serve as Subject.
