It is a summation of 17 Rakahs distributed as follows: 4 Sunnah (Ghayr-Mauqida - Not-emphasized) 4 Fardh (Obligatory with explicit proofs) 2 Sunnah (Mauqida - Emphasized) 2 Nafl (Voluntary) 3 Witr (Wajib - Obligatory with derived proofs) 2 Nafl (Voluntary) And Allah knows best.