Adpositions constitute a word class that only appears either before or after a complement (noun, noun phrase, pronoun, or clause serving as a noun phrase). Appearing before a complement they are prepositions; appearing after they are postpositions. The function of adpositions is to express the relationship between their complement and another noun or verb phrase, as well as express semantic relations such as place, time, ownership, instrument, and possession.[1] Adpositions are heads, and the nouns or noun phrases that they modify are the complements or objects of the adpositions.
In certain cases adpositions have a weak or strong effect on the form that the complement takes (i.e., case).[2] It may also happen that the adposition shows agreement with its complement.[3]
Types:
Adp=V: Adpositions are in fact verbs; they change according to verbal categories: tense, mode, aspect. Their complements are regular verbal arguments. (When this parameter value applies, there are two verbs – the adposition and the main predicate of the sentence – to which the entire adpositional structure is subordinate.)
Adp=NNonGov: Adpositions do not behave like verbs. Their complements appear in base form without inflection.
Adp=NStGov: Adpositions do not behave like verbs. Regardless of the specific adposition used, its complement always appears in the same non-base form: the standard case triggered by adpositions.
Adp=NGov: Adpositions do not behave like verbs. Their complements appear in various cases depending on the particular adposition in question.
AdpInfl: Adpositions show some form of grammatical agreement with their complements.[4]
[1]This function can be served not only by adpositions but also lexically or syntactically (e.g., conjugated verbs or declined nouns, case endings, adverbial affixes, and clitics). Some of these can be derived from adpositions, but as bound forms they cannot be considered true adposition or heads. Nor do they have their own person marking. (In forms like both the Hungarian ház-am-ban (house-Px.S1- INE) and the Finnish talo-ssa-ni, (house-INE-Px.S1) ‘in my house’ despite the different morpheme order, the personal affix codes the noun, not case, in contrast to postpositions in these languages that bear true person marking.) The adposition is therefore a separate word class; it is morphologically independent and shows morphosyntactic behavior in which in the given language it clearly differs from that of verbs, (declined) nouns, and adverbs.
[2] In the case of weak influence, the complement noun always appears in the same non-base form alongside any adposition; e.g., all prepositions trigger use of the same non-nominative case. In the case of strong influence, the complement noun can take multiple forms, determined by the adposition in question.
[3] The features of the majority of a given language’s dominant adpositions can be attributed to the language itself. If the frequent occurrence makes this impossible, dominant and recessive relationships should be marked with the use of a slash (/).
[4] If this value occurs simultaneously with the value AdpNNonGov, it should not be marked. If, however, the adposition and the noun mutually trigger in each other the use of specific cases, this should be marked with the use of a plus sign (+) and no space. For example, AdpInfl+AdpNStGov indicates that adposition shows some kind of agreement with its syntactically dependent noun, but the noun also shows agreement with the adposition, insomuch as the noun takes the standard adpositional case solely due to the presence of the adposition. Agreement with the adposition should be described in the commentary.