Combinations of final न् n.
204. Final radical n is assimilated in internal combination to a following sibilant, becoming anusvāra.
Thus, váṅsi, váṅsva, váṅsat, maṅsyáte, jíghāṅsati.
a. According to the grammarians, it is treated before bh and su in declension as in external combination. But the cases are, at best, excessively rare, and RV. has ráṅsu and váṅsu (the only Vedic examples).
b. Final n of a derivative suffix is regularly and usually dropped before a consonant in inflection and composition—in composition, even before a vowel; and a radical n occasionally follows the same rule: see 421 a, 439, 1203 c, 637.
c. For assimilation of n to a preceding palatal, see 201.
The remaining cases are those of external combination.
205. a. The assimilation of n in external combination to a following sonant palatal and the palatal sibilant ç have been already treated (202 b, 203).
b. The n is also declared to be assimilated (becoming ṇ) before a sonant lingual (ḍ, ḍh, ṇ), but the case rarely if ever occurs.
206. A n is also assimilated to a following initial l, becoming (like m: 213 d) a nasal l.
a. The manuscripts to a great extent disregard this rule, leaving n unchanged; but also they in part attempt to follow it—and that, either by writing the assimilated n (as the assimilated m, 213 f, and just as reasonably) with the anusvāra-sign, or else by doubling the l and putting a sign of nasality above; the latter, however, is inexact, and a better way would be to represent the two l's, writing the first with virāma and a nasal sign above. Thus (from trīn lokān):
manuscripts त्रींलोकान् or त्रीँल्लोकान्; better त्रील्ँ लोकान्.
The second of these methods is the one oftenest followed in printed texts.
207. Before the lingual and dental sibilants, ṣ and s, final n remains unchanged; but a t may also be inserted between the nasal and the sibilant: thus, tā́n ṣáṭ or tā́nt ṣáṭ; mahā́n sán or mahā́nt sán.
a. According to most of the grammarians of the Prātiçākhyas (not RPr.), the insertion of the t in such cases is a necessary one. In the manuscripts it is very frequently made, but not uniformly. It is probably a purely phonetic phenomenon, a transition-sound to ease the double change of sonant to surd and nasal to non-nasal utterance—although the not infrequent cases in which final n stands for original nt (as bharan, abharan, agnimān) may have aided to establish it as a rule. Its analogy with the conversion of n ç into ñch (203) is palpable.