If the root is a heavy syllable (having a long vowel, or a short before two consonants), the vowel of the reduplication is short: and in this case अ a or आ ā, and ऋ ṛ (if it occurs), are reduplicated by अ a.

a. Thus, adidīkṣam, abubhūṣam (not quotable), adadakṣam, adadhāvam, atataṅsam. And, in the cases in which a root should both begin and end with two consonants, both syllables would be necessarily heavy, notwithstanding the short vowel in the former: thus, apapraccham, acaskandam (but no such forms are found in use).

b. A medial ṛ is allowed by the grammarians to retain the strengthening of the causative stem, together with, of course, reduplication by a: thus, acakarṣat, avavartat (besideacīkṛṣat, avīvṛtat); but no such forms have been met with in use.

c. These aorists are not distinguishable in form from the so-called pluperfects (817 ff.).