The substitute aś comes in the place of etad when a prāgdiśīya affix follows.,
The श् of अश् causes the replacement of the whole 1.1.55. According to Patanjali the substitute is अन् and not अश् ॥ Thus एतद् + तसिल् = अतः 5.3.7; अत्र 5.3.10.
Vart:- This sutra must be divided into two एतदः, and अश्, the meaning being. (1) The substitutes एत and इत् come in the place of एतद् when affixes beginning with र् and थ respectively follow, as एतद् + र्हिल = एतर्हि 5.3.21 एतद् + थमु = इत्थम् ॥ The थ must be the थ of थमु which comes after idam 5.4.24 for the application of this rule (1), and not the थ of थाल् 5.3.23 before which the substitute will be अश् ॥ The word एतद् will take थमु by the implication af this rule. (2) The substitute अश् replaces एतद् before other Pragdisiya affixes.,