 For Kātyāyana and Patañjali, the level of padas (“inflected words”) is the basic level of language for grammar. These words are freely combined by the users to form sentences or phrases. The words are not derived by Kātyāyana and Patañjali by abstracting them from sentences by using the method of anvaya-vyatireka (“concurrent occurrence and concurrent absence”) (Vārttika 9 on P. 1.2.45). On the other hand, they claim that a grammarian first derives stems and affixes by applying the procedure of abstraction to words, and then in turn puts these stems and affixes through the grammatical process of derivation (saṃskāra) to build the words. Here, Kātyāyana and Patañjali do make a distinction between the levels of actual usage (vacana) and technical grammatical analysis and derivation. While full-fledged words (pada) occur at the level of usage, their abstracted morphological components do not occur by themselves at that level. However, they do not seem to suggest that the stems, roots, and affixes are purely imagined (kalpita).