Specifying a term on a semantically empty base

The term that the relative clause helps to form may either have a lexical core or not. If it has one, this is the head nominal of the relative clause, which modifies it. If it has none, the relative clause can modify an empty head, as in .a. This is a headless relative clause.

.	a.	Chi non ha mai imparato a lavorare l'impara all'università.
Ital	b.	Coloro che non hanno mai imparato a lavorare l'imparano all'università.

There is also the possibility of substantivizing the adjectival formed by the relative clause. Several languages including Italian cannot use the naked relative clause as an NP but must provide it with a determiner. This is shown in .b. Contrary to appearances, coloro is not the head noun. If it were, then since coloro is definite, the relative clause would have to be appositive, which it is not.

One construction remains to be singled out:

The main clause has a non-verbal predicate (i.e. it is a nominal or copula clause).
The subject is a relative construction with empty head.
The predication states identity of the subject with the predicate nominal.

E16 is an example:

E16.	What lay on the table was the tissue.

This construction, with contrastive stress on the predicate nominal, is a pseudo-cleft sentence. It generally serves as a focus construction.