I recently came across this term, which was new to me, in a rather old, but rather good grammar book - Advanced English Practice by BD Graver (Oxford). I can only find one reference to it on the Internet, at the also rather good Polseguera.com, a Catalan website for English learners (links below).
Update - since writing this, I've discovered that coordinate relative clauses are also (and probably more often) referred to as connective relative clauses. I've added a few more links at the end.
Coordinate (or connective) relative clauses look similar to non-defining relative clauses, and follow the same rules as non-defining clauses. Indeed some people would classify them as a sub-species of non-defining clauses. But there are a couple of subtle though key differences between classic non-defining relative clauses and coordinate relative clauses.
- 1. While standard relative clauses tell us something about the noun they are modifying (the antecedent) , coordinate relative clauses give us new information
- 2. We don't use standard non-defining relative clauses in spoken English very much, their being seen as rather formal. But coordinate relative clauses are often used in spoken and as well as written language.
This post should be considered more as an exploration of one small area of English grammar, than as a lesson. There is so little literature available on coordinate relative clauses, that I have had to largely rely on my own judgement. If anyone spots any glaring mistakes, please let me know.