A verb that is a copula is sometimes called a copulative or copular verb. Lexical verbs are categorizes into five categories&colon; copular, intransitive, transitive, ditransitive, and ambitransitive. The other three types of copular clauses do not involve predication. In copular sentences, the nominative is used for both subject and predicate. Conversely, these languages allow the copular verb in non-present sentences. Equatives equate the referents of the two expressions on either side of the copular verb. In all other instances the copular verb acts regularly. Like Spanish, it has two main copular verbs&colon; "ser" and "estar". The copular subject will be in the nominative case, the copular complement in the oblique. Other special uses of copular verbs are described in some of the following sections. Then too, if no other auxiliary or copular verb is present, "do"-support is required. Constituent order "within" a clause is generally free, apart from copular clauses. The copular forms are very similar to their Standard German counterparts.