Up to yathātathayathāpurayoḥ paryāyeṇa [[7.3.31]] inclusive, the substitution of vṛddhi will take place for the first vowel of the second member in a compound.,
This is an adhikara sutra, and exerts governing influence upto 7.3.32 exclusive. The phrase \of the second member of the compound\ should be supplied in all those sutras, to complete the sense. Thus in 7.3.11, the word उत्तरपदस्य should be supplied. As पूर्ववार्षिकं, अपरवार्षिकम्, पूर्वहैमनम्, अपरहैमनम् ॥
In those sutras, where the word denoting the first member is not exhibited in the Ablative case, as in 7.3.18, 7.3.19, 7.3.20, 7.3.21, the present sutra is absolutely necessary for causing the vriddhi of the second member. But in those sutras, where the first member is exhibited in the ablative case, as in 7.3.11 (अवयवात्), there this sutra is only explanatory (and not absolutely necessary), and serves also the purpose of placing such vriddhis under the category of 'uttarapada-vriddhi'. This peculiar vriddhi is liable to certain rules of accent, as in 6.2.105. Hence the importance of the present aphorism in those sutras also, where the word is exhibited in the fifth case.,