… the environments of manifestation can be differentiated in terms of
(i) metafunction — textual (conjunction), logical (interdependency; modification) and experiential (circumstantiation; process type: relational), and
(ii) rank — clause and group/phrase [and below]. …
Collectively they thus construe expansion as a semantic system. This means that for any given type of expansion we want to express, we have at our disposal a range of resources.