The affix aṇ -- prāgdīvyato'ṇ [[4.1.83]], comes after a word in the Genitive -6th-Case in construction in the sense of 'any body'sūtras sphere', if a country is indicated by such sphere.,
The anuvritti of समूहः 4.2.37 does not extend further : but the anuvritti of तस्य 4.2.37 is to be read into it. The whole sutra thus becomes तस्य विषयो देशे 'his sphere-in denoting a country'. The word विषय 'sphere, topic' has many significations. Sometime it means an estate, as विषयो लब्धः, 'a village has been acquired'. Some time it means an object of perception, as चक्षु र्विषयो रूपं 'color is the object of sight' &c. Therefore the word देश has been used in the Sutra, in order to fix the particular meaning of the word विषय ॥
Thus शिबीनां विषयो देशः = शैवः 'The country within the sphere of the Sibi'. So also औष्ट्रः &c. Why do we say 'if a country is meant'? Observe देवदत्तस्य विषयोऽनुवाकः ॥,