The affix ḍhak optionally comes after the words 1. phālgunī 2. kārttikī and 3. caitrī being the names of full-moon nights, the whole word so formed being a Name denoting a division of time (a month, a fortnight or a year) in which the moon is full.,
Thus फाल्गुनः or फाल्गुनिकः, श्रावणः or श्रावणिक, कार्तिकः or कार्तिकिकः, चैत्रः or चैत्रिकः ॥ This optionally ordains ठक् instead of अण् ॥,