आद्युदात्तश्च

That which is called an affix has an acute accent on its first syllable.
This sutra may also be treated as a Paribhasha or an Adhikara sutra. The udatta accent falls on the affix, and if it consists of more than one vowel, then on the first of the vowels. Thus the affix तव्य has udatta on the first अ as in कर्त्तव्यम्. This general rule of accent applies only where there is no special rule laid down. Thus, rule (VI.I.163), declares that affixes having an indicatory च will have udatta on the final; those having an indicatory र have accent on the middle (VI.I.217); those that have an indicatory प are anudatta; those having an indicatory ज, throw the acute accent on the syllable immediately preceding the affix (VI.I.193); the affixes having an indicatory प्र and न throw the acute accent on the first syllable of the word to which they are added (VI.I.197); the taddhita affix having an indicatory क takes acute accent on the final (VI.I.165); and the affix having an indicatory त is svarita (VI.I.185).