Vocalic alternations in the Sanskrit morphological system is termed "strengthening", and called "guṇa" and in the preconsonantal versions. There is an equivalence to terms deployed in Indo-European descriptive grammars, wherein Sanskrit's unstrengthened state is same as the zero-grade, "guṇa" corresponds to normal-grade, while is same as the lengthened-state. The qualitative ablaut is not found in Sanskrit just like it is absent in Iranian, but Sanskrit retains quantitative ablaut through vowel strengthening. The transformations between unstrengthened to "guṇa" is prominent in the morphological system, states Jamison, while is a particularly significant rule when adjectives of origin and appurtenance are derived. The manner in which this is done slightly differs between the Vedic and the Classical Sanskrit.