203. Before the palatal sibilant

Before the palatal sibilant श् ç, both त् t and न् n are assimilated, becoming respectively च् c and ञ् ñ; and then the following श् ç may be, and in practice almost always is, converted to छ् ch.

Thus, vedavic chūraḥ (-vit çū-), tac chrutvā, hṛcchaya (hṛt + çaya); bṛhañ cheṣaḥ or çeṣaḥ, svapañ chete or çete.

a. Some authorities regard the conversion of ç to ch after t or n as everywhere obligatory, others as only optional; some except, peremptorily or optionally, a ç followed by a mute. And some require the same conversion after every mute save m, reading also vípāṭ chutudrī́, ā́naṭ chúci, anuṣṭup chāradī, çuk chuci. The manuscripts generally write ch, instead of cch, as result of the combination of t and ç.

b. In the MS., t and ç are anomalously combined into ñ ç: e.g. táñ çatám, etāvañçás.