The a of ahan is elided only before the affixes ṭa and kha,
Thus द्वे अहनी समाहूते = द्व्यहः, त्र्यहः (5.4.91 with टच्), द्वे अहनी अधीष्टो भृतो भूतो भावी वा = द्व्यहीनः, त्र्यहीनः (with ख 5.1.87).
Vart:- ख is added to अहन् in the sense of तस्य समूहः, when referring to a sacrifice. अह्नां समूहः क्रतुः = अहीनः 4.2.42.
Though the अन् of अहन् would have been elided by the last aphorism also, before the affixes ट and ख, the present sutra makes a restrictive rule : अहन् does not lose its final अन् before any other Taddhita affix, thus अह्ना निर्वृत्तम् = आह्निकम् (with ठञ् 5.1.79). The word एव 'only' is for the sake of perspicuity. अहन् alone does not lose its final अन् before ट and ख, other stems also do the same. This we infer, from the exception made in the case of atman and adhvan, before ख in 7.4.169.,