Halliday & Matthiessen (1999: 212):
Qualities of enhancement also resemble those of ‘elaboration: identity’ and those of extension in that construe a relation between a thing they are assigned to and another thing. This is brought out by the fact that they are agnate with processes relating participants circumstantially: subsequent : be (come) before / precede, interior : be within, exterior : be outside, as in previous occasions : occasions coming before this one, interior design : design is what is within a house.