Clause Finiteness & Dependency

Halliday & Matthiessen (2004: 423, 424):

A finite clause is in principle independent; it becomes dependent only if introduced by a binding (hypotactic) conjunction. If it is joined in a clause complex, its natural status is paratactic. In this case its logical-semantic relationship to its neighbour is typically shown by a linking (paratactic) conjunction. …

A non-finite clause, on the other hand, is by its nature dependent, simply by virtue of being non-finite. It typically occurs, therefore, without any other explicit marker of its dependent status. Hence when a non-finite clause occurs without a conjunction, there is no doubt about its hypotactic relation in a clause complex; but there may be no indication of its logical-semantic function.

Adverbial Conjunctions

Halliday & Matthiessen (2004: 419):

Adverbial conjunctions are as/so long as, as/so far as, (as) much as, for example as long as you’re here …, as far as I know …, much as I’d like to … (compare non-finite as well as, which is extending not enhancing.  In origin these express limitation, a particular point up to which a certain circumstance is valid.

Nominal Conjunctions

Halliday & Matthiessen (2004: 419):

Nominal conjunctions include in case, in the event that, to the extent that, and the + various nouns of time and manner, eg the day, the moment, the way.  These last have evolved from prepositional phrases with the enhancing clause embedded in them, eg on the day when we arrived; but they now function to introduce hypotactic clauses just like other conjunctions, eg their daughter was born the day we arrived, the way they’re working now the job’ll be finished in a week.  Note that they no longer have the nominal group potential for modification; thus while we can say on the beautiful day when we arrived, it would be odd (or impossible) to say their daughter was born the beautiful day we arrived.

Verbal Conjunctions: From Projection To Expansion

Halliday & Matthiessen (2004: 419):

Verbal conjunctions are derived from the imperative or from the present/active or past passive participle + (optionally) that: provided (that), seeing (that/how), suppose/supposing (that), granted (that), say (that).  In origin these are projections; their function as expanding conjunction reflects the semantic overlap between expansion and projection in the realm of ‘irrealis’: ‘let us think/say that’ = ‘if …’, as in say they can’t mend it, shall I just throw it away?.

Three Kinds Of Complex Conjunction

Halliday & Matthiessen (2004: 419):

As well as simple conjunctions such as because, when, if, and conjunction groups groups like as if, even if, soon after, so that, there are three kinds of complex conjunction, one derived from verbs, one from nouns and the third from adverbs.