Rule. This sūtra is an adhikāra, a heading. Before the sūtra tena krītam "bought with that" (SK 1702), the affix cha is the governing affix. The heading stops before that sūtra, so tena krītam itself is outside it. The word krīta names that sūtra by one of its words.
Cha is heard as īya (SK 475). It has no marker ñ or ṇ, so it brings no vṛddhi, the replacement of the base's first vowel by ā, ai or au (SK 1075).
Example. The heading's cha shows in the forms where no exception applies:
vatsebhyo hitaḥ "good for calves" → vatsa + cha
→ ch → īy → vatsa + īya
→ vatsa is a bha stem, a stem before an affix beginning with a vowel or y; its final a is deleted (SK 311) → vatsīyaḥ.
Applies when / blocked by. Bhaṭṭoji's commentators explain what the heading bounds. It bounds senses, not affixes. The sūtras up to tena krītam state senses, and cha is present in each of them. One of them draws the consequence. When a rule gives a particular affix to a particular base in the same sense, that affix sets cha aside for that base. The two do not alternate. Cha keeps the bases for which no special affix is named.
Watch out. This chapter covers only the first part of the heading's range. Its last line says that the range of cha and yat is complete (SK 1679). The heading itself runs on to SK 1702, but the rules after this chapter name their own affixes.
Before 'tena krītam' (SK 1702), cha is made the governing heading (adhikāra).
- commentary BM opens the fifth adhyāya here. BM: the word krīta stands for the sūtra that contains it (taddhaṭitasūtra-para), as the kaumudī's 'tena krītam' shows; in the sūtras before 'tena krītam' only senses (artha) will be stated, not affixes, and in those 'cha' is present (upasthita). Followed for '[the sūtra containing the word] krīta' in sutra_en and for taking 'prāk' as 'before', i.e. up to but not including SK 1702.
- commentary TB, printed under sk.1660.t1 (after the close of the prāgghitīya section, whose TB colophon the OCR gives as 'iti prāgvidhatīyāḥ samāptāḥ', and after TB's 'samāptāś cāturarthikāḥ'): on 'ity ataḥ prāk', what is taken as the limit here is the sense (artha), not the affix or the base; so only senses are bounded, i.e. cha is present in the senses hita etc. before krīta, since the bounded is of the same kind as the limit (as in 'māsāt' a time, 'grāmāt pūrvaḥ' a place, 'alo 'ntyāt pūrvaḥ' a sound). Consequently a yat etc. arising in the same sense from a particular base blocks cha, which has scope with other bases, by the takra-kauṇḍinya maxim; otherwise cha and yat etc. would alternate like tavya and anīyar. TB then rejects the alternative of relying on the vibhāṣā of 'vibhāṣā havirapūpādibhyaḥ' (SK 1664) as an indicator (jñāpaka), since then the adhikāra could simply be 'chaḥ' with no limit stated. Followed in rendering 'adhikriyate' as a heading that governs the senses stated up to SK 1702, without making the limit an affix.