Sentence:  The chapter focuses on the <WSD>supine</WSD> clause, which is a language-specific construction. An example is offered in (1): the aspectual verb "isprăvi" 'finish' selects a clausal complement that contains a <WSD>supine</WSD> verb. We know that the <WSD>supine</WSD> is a verb because its direct object is in unmarked Case (i.e. Accusative). <WSD>Supine</WSD> nouns, like any regular noun, have the direct object marked for Genitive Case. ... The emergence and the spread of the <WSD>supine</WSD> clause is very well captured in the Old Romanian texts, a situation that contrasts with the incomplete information we have about other clausal complements. 
Meaning of the word marked with <WSD> tags:  In Latin and other languages: a type of verbal noun used in the ablative and accusative cases, which shares the same stem as the passive participle.