Praudhamanorama p163

p163

"*sima* occurs in [the senses of] 'whole', 'capable', 'boundary', and 'bound'". And it is heard [in the Veda]: *ādrātro vāsastanute simasmai*, *ucchukramatkamajate simasmāt*. In both places, the word *sima* is a synonym of *sarva* ('all'), according to the Vedic commentary.
[On the words] "in the gaṇasūtra": even though in the Mahābhāṣya the vārttika *apurīti vaktavyam* is read under the rule belonging to the Aṣṭādhyāyī, nevertheless it is supplementary to the gaṇasūtra, and not to that which prescribes the option before *jas*. For since the substitution of *śī* in place of *jas* is prescribed under the governing influence of *ataḥ* (after an *a*-stem), it would not apply after what ends in *ṭāp*.
On the words "antarāyām": the meaning is, "outside the rampart or situated inside it." Its applicability is to be understood either through the metarule regarding [stems] characterized by gender, or because a single substitute is apprehended as having the nature of the end of the preceding member.
The words 'tyad' and 'tad' refer to what has been mentioned. There, the author of the Gaṇaratna says that the first is Vedic. That is incorrect, because it would entail that the mention of "in the Veda" in the rule "syaś chandasi bahulam" (Pā. sū. 6.1.181) would be superfluous.