Short a is optionally substituted for the vowel of the reduplicate in the reduplicated Aorist of the Causative of veṣṭ and ceṣṭ,
Thus अववेष्टत् or अविवेष्टत्, अचचेष्टत् and अचिचेष्टत् ॥ In one alternative there is shortening of the reduplicate 7.4.59, and after such shortening, there is अ substituted in the other alternative.,