Let us consider some examples from Group B. 1.1.47 mid aco’ntyāt paraḥ teaches that an item marked with anubandha M is placed after, i.e., to the right-hand side of, the last vowel of the item to which it is added. 1.1.51 ur aṇ raparaḥ teaches that r is added after, i.e., to the right side of the vowels a, i, u when they are substitutes of r̥. 1.1.54 ādeḥ parasya teaches that a substitute taught for the following or right-hand side item replaces its first sound. From these examples, it becomes clear that in the rules I have listed under group B, para is used to mean ‘right-hand side’ in the context of Pāṇinian derivations.

Let us confirm this by considering some rules which contain both pūrva and para. 6.1.84 ekaḥ pūrvaparayoḥ teaches that (in the following rules) a single sound replaces both the LHS sound and the RHS sound in case of saṁhitā ‘immediate proximity’. Similarly, 1.1.57 acaḥ parasmin pūrvavidhau teaches that a substitute for a vowel, if it is conditioned by an RHS context, is treated like its substituendum with respect to an operation on an LHS element.

This leads to an important question: if traditional scholars interpreted para as ‘RHS item/operation’ in so many metarules as shown above, why did they interpret it as ‘the following rule’ in 1.4.2?[1] I think this misunderstanding possibly arose because another metarule, 8.2.1 pūrvatrāsiddham, uses pūrva, the opposite of para, to mean ‘preceding rule’. 8.2.1 teaches that from 8.2.1 onwards, a preceding rule treats a following rule as suspended. This may have led Kātyāyana, the first scholar to comment upon Pāṇini’s sūtras, to think that, in sūtras dealing with relationships between rules such as 8.2.1 and 1.4.2, pūrva and para mean preceding rule and following rule respectively. However, upon closer examination, one realizes that when Pāṇini wants to indicate that he is referring to the relationship between preceding and following rules rather than operands, he adds the affix traL to the base: he says pūrva-tra in 8.2.1.