Wasl expresses the connection of clauses through coordinating wāw. Fasl leaves that link unexpressed. These are not merely syntactic preferences: they affect meaning, attribution, and listener interpretation.
The two contexts of wasl concern full suitability and avoidance of misunderstanding. The five kinds of fasl concern complete unity, complete disconnection, implicit answer, misleading attribution, and an impediment to shared grammatical scope.
The next chapter addresses ijaz, itnab, and musawat: the relationship between how much is expressed and how much meaning is conveyed.