प्राग्दिशो विभक्तिः

The sūtra taught from this forward up to दिक्शब्देभ्यः सप्तमीपञ्चमीप्रथमाभ्यो दिग्देशकालेष्वस्तातिः 5.3.27 (exclusive) are called विभक्ति।
The affixes herein taught do not change the sense of the word, i.e. they are स्वार्ध affixes which leave to the word their own denotation. The rule 4.1.82, extends no further than this, hence the words formed by these affixes do not produce epithets connoting the sense of the primitive and denoting something else.

Thus 5.3.7 declares, that after the words किम् in the ablative there is the affix तसिल्, as कुतः, ततः, यतः ॥

The purpose served by designating these affixes as Vibhakti is (a) to debar the elision of final स् and म् of the affixes as इत् (1.3. 4). Thus in the affix दानीम् 5.3.18, म् is not इत्, had it been so, rule 1.1.47 would have applied: (b) to regulate the accent of इदम्, thus इदम् + तसिल् = इतः here by 6.1.171, the affix तसिल् becomes udatta by virtue of its being Vibhakti, othewise the accent would have been regulated by the indicatory ल् 6.1.193; (c) to make applicable to these words the rules of त्यदादि, that is, the rules given in the Sutras 7.2.102, and those that follow. Thus त्यद् + तसिल् = त्यतः, the द being replaced by अ by 7.2.102.

The affixes now to be taught being स्वार्थिकः, the anuvritti of समर्थानाम् and प्रथमाद् of 4.1.82, does not apply to them. The word वा of 4.1.82 however applies here, so that these affixes are optional, thus we may have कुतः or कस्मात्, कुत्र or कस्मिन् ॥