anaṅ (an) is substituted for the final of the aṅga (stems) ending in ṛ as well as for the final of 1. uśanas 2. purudaṃśas and 3. anehas in the Nominative 1st-Case singular (but not in the Vocative Case singular).,
Karika:-
संबोधने तूशनसस्त्रिरूपं सान्तं तथा नान्तमथाप्यदन्तम् ॥
माध्यं दिनिर्वष्टि गुणं विगन्ते नपुंसके व्याघ्रपदां वरिष्ठः ॥
As कर्ता, हर्ता, माता, पिता, भ्राता, उशना, पुरुदंशा, अनेहा ॥ In the Vocative Singular we have हे कर्तः, हे मातः, पितः पुरुदंशः, अनेहः and उशनः ॥
Vart:- अनङ् is substituted for the final of उशनस् in the Vocative Singular also, as हे उशनन्, the final न् not being elided (See 8.2.8). Otherwise we have हे उशन ! Thus it has three forms in the Vocative Singular : as हे उशनस्, हे उशनन्, and हे उशन ! ॥
Karika:- In the vocative, the word उशनस् has three forms, (1) ending in स् when अनङ् is not added, (2) ending in न्, when न् is not elided, (3) ending in अ when न् is elided. This is the opinion of the Acharya Madhyandini. So also according to the Acharya Vaiyaghrapadya, (the best of the Vyaghrapadas), there is Guna in the Neuter of the stems ending in इक् vowels; as हे त्रपो ॥
The त् in ऋत् is for the sake of distinctness.,