niyamavidhi and parisāmkhyavidhi

Niyamavidhis ("restrictive prescription"; for definitions and examples, see a preceding post and the comments thereon) can be found also in Grammatical literature. Sabara mentions them at least in two places (his commentary on 6.8.31 and 32).
The concept of parisamkhya is also ancient enough. I read about it in Sabara and in Kaiyata´s commentary on Patanjali´s Paspasā. The typical example mentioned is panca pancanakha bhaksya, that is "the five animals having 5 nails (or claws?) can be eaten" which indirectly implies that all other animals cannot be eaten.
Both are described in Kumārila´s Tantravārtika (on 1.2.4.38) and are later to be found in Parthasarathi Misra, Appayadiksita (who dedicates to them his whole Vidhirasāyana), Gāgābhatta´s Bhattacintamani. Sankara Bhatta mentions them in his Mimāmsābālaprakāsa together with tens of other kinds of prescriptions. More interesting, both the Arthasangraha and the Mimāmsānyāyaprakāsa mention them within their discussion about mantras. The Arthasangraha does not explain why, whereas the MNP makes the connection explicit. One could be inclined to think that mantras have more than one purpose, but it is not so because of a niyamavidhi stating that mantras are meant to make one remember the various elements of a ritual performance.
Moreover, the AS states that parisāmkhyavidhi is affected by two flaws, since it implies a meaning partly contradicting what is explicitly found in the Sacred Texts. Hence, parisāmkhyavidhi is a sort of extrema-ratio-vidhi, a last resource in case one need to make sense of an otherwise meaningless prescription. Possibly because of this reason, it is not mentioned in Rāmanujācārya´s Tantrarahasya and it does not seem to have been regularly implemented in Vedic exegesis.