A construction of the category ‘nominal’ may be formed in the following ways:

1. A nominal (in particular, a noun) may be combined with an attribute:
1. an adjectival attribute
2. a nominal attribute
3. an adverbial attribute
4. an adnominal subordinate clause
• a relative clause
• an adnominal substantive clause.
2. A nominal or NP may be accompanied by another one in apposition.
3. A clause may be nominalized.

In case #1, the head may be empty, be it by zero anaphora, be it by substantivization of the attribute. The result is not necessarily structurally complex, but is, at any rate, complex in terms of the operations involved.