And the affix ṭhañ also (as well as yat) comes in the remaining senses after the word arddha when the prior term denotes a direction.,
By च, the affix यत् is also used. This debars अण् ॥ Thus पूर्वार्ध्यम्, पौर्वार्धिकम्, दक्षिणार्ध्यम् or दाक्षिणार्द्धिकम् ॥
The word पद is used in the sutra in order to prevent ambiguity. Had the sutra stood merely as दिक्पूर्वाट् ठञ्च, it might have meant 1.1.68, 'Ardha preceded by the word दिक् takes ठञ् also', for then स्वरूपविधि would have applied, and दिगर्धे जातः would have taken the affix.,