This section briefly discusses the linker element om that introduces om + te-infinitivals. The fact that om is optional in argument clauses has given rise to the claim that om is superfluous and should in fact be avoided, as was stated in the beginning of the 20th century by Den Hertog (1973:74-5). His advice was in fact not merely motivated by the optionality of om, but also because that he analyzed om as a regular preposition. Since subjects and direct objects are normally not introduced by the preposition om, the use of this preposition is claimed to be improper with infinitival subject and object clauses. Similarly, since prepositional objects are already introduced by fixed prepositions, the use of the additional preposition om with PO-clauses is claimed to be pleonastic in nature.
      The claim that the linker om is prepositional in nature has also been defended in more recent years. Bennis & Hoekstra (1985), for example, argue for the prepositional status of om on the basis of the distribution of om + te infinitivals. Their point of departure is the observation extensively discussed in Section 5.2.1.1 that such infinitivals have the same distribution as finite clauses in their use as arguments of verbs, nouns or adjectives. There is, however, one conspicuous difference in the distribution of finite clauses and infinitival clauses preceded by om; whereas the former can be used as the complement of a preposition, the latter cannot. This is clear from the fact that examples such as (366b) are only acceptable if om is omitted.

Bennis & Hoekstra relate the ungrammaticality of example (366b) with om to the more general restriction that PPs normally cannot function as complements of prepositions; see Section P2.2, where we also discuss a small number of exceptions. If the linker element om is indeed prepositional, the contrast indicated in (366b) is covered by the same generalization.
      A potential problem for the assumption that the linker element om is a preposition is that om does not add a clearly discernible meaning contribution; see Den Hertog's claim that om is superfluous. Therefore, if om is to have any function, it must be a syntactic one; this is explicitly stated by Dik (1985), who analyzes om as a relator, that is, an element marking a relation of syntactic dependency (selection). This position is not necessarily incompatible with the claim that om is prepositional in nature, given that prepositions are also used as relators when heading a prepositional object; like om in om + te-infinitivals, the functional preposition op in Jan jaagt op herten'Jan hunts for deer' is semantically void and primarily used to indicate the thematic relation between the verb jagen'to hunt' and the noun phrase herten'deer'. However, by categorizing om as a relator, Dik analyzes it as a functional element comparable to the complementizer dat'that', which likewise signals a relation between a matrix verb and a syntactic dependent, viz., a finite argument clause.
      The claim that the linker element om functions as a complementizer-like element is compatible with Bennis & Hoekstras analysis since they do not claim that om heads an independent PP, but instead they situate it in the complementizer domain of the dependent clause. Pronominalization provides empirical evidence for the complementizer status of om; the examples in (367) show that the om + te infinitival behaves like a clause in that it must be pronominalized by het'it', and cannot be pronominalized by erom, which would be expected if om were a regular preposition.

Assuming that om functions as a complementizer is also compatible with attempts in generative grammar to provide a unified treatment of functional prepositions and complementizers. Since discussing this would lead us too far into complex theory-internal discussions, we refer the reader to Emonds (1985:ch.7) and Kayne (2000:part III) and simply conclude that om is a kind of in-between category; it is a preposition with complementizer-like properties or, vice versa, a complementizer with prepositional properties. This may be sufficient to account for the unacceptability of examples such as (366b) with om, while still avoiding the problem signaled by Den Hertog.
      It should be pointed out that the acceptability contrast between infinitival clauses with and without om in (366b) shows that the omission/addition of om is not always innocuous. The same thing is shown by the fact illustrated in (368) that omitting om may make an infinitival object clause transparent; whereas (368a) shows that the complete clause preceded by om must follow the matrix verb in clause-final position, (368b) shows that the clause without om can be split by it. In the remainder of our discussion of om + te infinitivals, we will abstract away from these effects, but we will return to them in Section 5.2.2, where we discuss te-infinitivals without om.

Finally, it is important to note that while it is normally always possible to omit om from infinitival argument clauses, it is not always possible to add it to infinitival argument clauses without om. Example (369), for instance, shows that the verb beweren'to claim' cannot take an om + te-infinitival as its complement. Such cases will also be discussed in Section 5.2.2.