Purpose sentences describe a relationship of two events, in which the main event must occur in order to allow the second, also known as the purpose event. In this type of sentence, the phrase or clause describing the purpose event is called the purpose construction. This construction may be either (a) a finite or nonfinite verb form (purpose complement), or (b) a clause (purpose clause). A purpose construction marker is an obligatory or optional strategy used to mark a construction as a purposive one, and it may appear as an independent grammatical word, affix, particle, or special verb form that would not appear in a simple declarative sentence.[1]

Types:

NoPurpMark: No grammatical strategies are used to mark a purpose construction; the causal relationship between the two events can be determined by contextual or pragmatic clues.

PurpV1: Purpose constructions are marked by a special verb form[2].

PurpV2: Purpose constructions are marked by a nonfinite verb form[3].

PurpAff: Purpose constructions are marked by a special affix on the verb.[4]

PurpClit: Purpose constructions are marked by a special clitic.[5]

PurpWV1: Purpose constructions are marked by an independent word (referent) in the main clause.[6]

PurpWV2: Purpose constructions are marked by an independent word (conjunction).

When a language displays more than one type, two values can be listed. If one type is dominant, a slash (/) can separate the two values, with the dominant value appearing first; if neither is dominant, they are listed with an ampersand (&) separating the two. The use of parentheses indicates that strategy is not obligatory, while the use of a plus sign (+) instead of an ampersand indicates that the two strategies must be used simultaneously.

[1] The function of this marker is not necessarily exclusive to marking purpose constructions.

[2] The special verb form must be distinguished from the base form in its tense, mood, aspect, person marking, affixes, or adpositions.

[3] This word may be an infinitive, participle, or noun derived from a verb.

[4] The special affix should be invariant (non-paradigmatic) in its form. Without it, the verb form would be identical to the form in which it appears in an independent (main) clause. In some cases, the special morpheme may appear as an affixed conjunction required in any subordinate clause.

[5] The clitic should be invariant (non-paradigmatic) in its form and does not necessarily attach to the verb. Without it, the verb form would be identical to the form in which it appears in an independent clause.

[6] This covers cases in which the sentence is not complex and those in which the marker appears obligatorily in the main clause rather than the purpose construction. The word class of the obligatory independent word should be specified in the commentary.