Definition: अाद्यन्तवद्भाव, consideration of a single or solitary letter as the initial or the final one according to requirements for opcrations prescribed for the initial or for the final. Both these notions --the initial and the final-are relative notions, and because they require the presence of an additional letter or letters for the sake of being called initial or final it becomes necessary to prescribe आद्यन्तवद्भाव in the case of a single letter; cf.अाद्यन्तवदेकस्मिन् । आदौ इव अन्त इव एकस्मिन्नपि कार्यं भवति । यथा कर्तव्यमित्यत्र प्रत्ययाद्युदात्तत्वं भवति एवमौपगवमित्यत्रापि यथा स्यात् । Kāś. on P.I.1.21; cf. also अाद्यन्तवच्च । अपृक्तस्य आदिवदन्तवच्च कार्यं भवति । T. Pr. I.55. This अाद्यन्तवद्भाव of Pāṇini is, in fact, a specific application of the general maxim known as vyapadeśivadbhāva by virtue of which"an operation which affects something on account of some special designation, which for certain reasons attaches to the letter, affects likewise that which stands alone;"cf. Pari.Śek. Pari. 30.