Coordinate clauses are units of equivalent syntactic status. Each of them has the force of an independent statement (proposition).
Main types of logico-semantic relations between coordinate clauses are copulative, adversative, disjunctive, causative, consecutive. They can be also found between simple sentences. This has given cause to some scholars to deny the existence of a compound sentence as a special structural type and treat it as a sequence of simple sentences. This idea is usually rejected, as a compound sentence is a semantic, grammatical and intonational unity. Each coordinate clause functions as part of this unity.
As coordination reflects the logical sequence of thought, the order of coordinate clauses is usually fixed: He came at 5 and we had dinner together.
The opening clause is most independent structurally, the following clauses may be to a certain extent dependent on the first clause - they may be elliptical, may contain anaphoric pronouns, etc.
Coordinating conjunctions and meanings rendered by them are described in Practical Grammar.
The classification of complex sentences is usually based on the classification of subordinate clauses. Subordinate clauses are classified either on analogy with classes of words (structural classification) or on analogy with parts of the sentence (functional classification).
Structural classification. Clauses are subdivided into
- noun clauses (substantive clauses),
- adjective clauses,
- adverb clauses, etc.
