How many parts are there in Sarf?

In Sarf, words are divided into seven kinds (Haft Aqsam) by their root letters: Sahih, Misal, Ajwaf, Naqis, Lafeef, Muza'af, Mahmuz By number of letters: Thulasi, Ruba'i, Khumasi (Mujarrad and Mazeed Feeh)