Śaunaka Śikṣā 11

11

vyañjanānāntvardhamātrā svarabhaktestathaiva ca
saṃyoge pādamātrā syātsvarabhaktiḥ prakīrtyate

The measure of consonants, however, is half a mora, and likewise of an anaptyctic vowel (svarabhakti). / In a conjunct, it is a quarter-mora; such is the anaptyctic vowel proclaimed to be.