The augment puk (p) is added to the roots 1. ṛ 2. hrī 3. vlī 4. rī 5. knuy 6. kṣmāya and to a root ending in long ā when the affix ṇi (the Causative) follows.,
As अर्पयति, ह्रेपयति, व्लेपयति, रेपयति, क्नोपयति, क्ष्मापयति ॥ The anuvritti of every word other than अङ्ग (VI. 4. 1.) ceases. The य् of क्नूय् and क्ष्माय् drops by 6.1.66. The guna takes place by 7.3.86. Of the roots ending in long आ, we have दापयति, धापयति ॥ The root ॠ (Bhuadi 983) गतिप्रापणयोः, and ॠ (Juhotyadi 16) गतौ are both meant here. Similarly री includes रीङ् स्रवणे (Divadi 30), and री गतिरेषणयोः (Kryadi 30). The augment is added at the end of the preceding stem of root, and not to the affix. Being added to the root it becomes part of the root-stem, and in forming the reduplicate Aorist of such stems, the vowel before प् is shortened by 7.4.1. If प् were not the part of the stem, that vowel would not be shortened. Thus from दापयति; we have Aorist अदीदपत् ॥,