Section 23, (p. 14) says,
"Two or more sentences, clauses, phrases, or single words, linked together by one of the conjunctions
and, but, or, nor, for, yet, only
are called co-ordinate, i.e. of the same rank; and the conjunctions which link them together are called co-ordinating conjunctions."
This is FANBOY with an extra o for only, FANBOYO, if you will.