Halliday & Matthiessen (2014: 497-8):
Here the relation between the embedded clause and the Head noun is a circumstantial one of time, place, manner, cause or condition. There are two types, according to where this relationship is construed: (i) those where the circumstantial sense is located in the embedded clause itself; (ii) those where it is located in the noun functioning as Head. With both these types, the embedded clause may be either (a) a relative clause or (b) an enhancing clause. The different combinations are set out in Table 7.13 below, for both (1) finite and (2) non-finite clauses.
