134. Unusual final

a. The diphthong o (except as phonetic alteration of final as: see 175 a) is an unusual final, appearing only in the stem go (361 c), in the voc. sing. of u-stems (341), in words of which the final a is combined with the particle u, as atho, and in a few interjections. In the last two classes it is uncombinable (below, 138 c,f); the vocatives sometimes retain the v and sometimes lose it (the practices of different texts are too different to be briefly stated); go (in composition only) does not ordinarily lose its final element, but remains gav or go. A final as becomes a, with following hiatus, before any vowel save a (for which, see the next paragraph).

b. The ब् v of आब् āv from औ āu is usually retained: thus,

तावेव tāv eva (tāu + eva);

उभाविन्द्राग्नी ubhāv indrāgnī (ubhāu + indrāgnī).

c. In the older language, however, it is in some texts dropped before an u-vowel: thus, tā́ ubhāú; in other texts it is treated like āi, or loses its u-element before every initial vowel: thus, tā́ evá, ubhā́ indrāgnī́.