The case affixes of the Instrumental and of the cases that follow it have the acute accent, if the stem in the Locative Plural is monosyllabic.,
The word सो (locative of सु) refers to the सु of the Locative plural. Thus वा॒॒चा, वा॒॒ग्भ्या꣡म्, वा॒॒ग्भिः꣡, वा॒॒ग्भ्यः꣡, या॒॒ता꣡, या॒॒द्भ्या꣡म्, या॒॒द्भिः꣡ ॥ Why do we say 'in the Locative plural'? Observe रा꣡ज्ञा, रा꣡ज्ञे ॥ Why do we say 'monosyllabic'? Observe हरि꣡णा, गिरिणा꣡, रा꣡जसु ॥ Why do we say 'the Instrumentals and the rest'? Observe वा꣡चौ, वा꣡चः ॥ Why do we say \the case-endings (विभक्तिः)?\ Observe वाक्तरा, वा꣡क्तमा ॥ The plural of the Locative being taken in the sutra, the rule does not apply to त्व꣡या and त्व꣡यि, as in the plural of the Locative they have more than one syllable, though in singular locative their stem has one syllable.,