The head noun in a complex noun phrase (cf. 1) can be modified by a number of structures:
finite clause
The man who came to dinner brought the flowers
-ing participle clause
The man coming to dinner tonight will bring the flowers
-ed participle clause
Any story written by Hemingway has a distinctive style
infinitive clause
That's a good place to eat
prepositional phrases
The tree behind the house needs trimming
adverbials
The way back was difficult
adjectives
Something funny happened last night
Postmodifying finite clauses are most often relative clauses, but they can also be appositive with head nouns like fact, proposition, reply, remark, answer, etc. The relationship of the appositive clause with the head noun is one of equivalence; compare:
The fact that he came (appositive clause)
The fact is that he came
The man who came to dinner (relative clause)
*The man is who came to dinner
Postmodifying infinitive clauses are usually analyzable as reduced relative clauses, but they can also be appositive. Compare:
the ability to speak French (appositive clause, = the ability is to speak French)
a good place to eat (reduced relative clause, = a good place where one can eat, not *a good place is to eat)