The semi-vowel of the affix vas (vaṃs) is vocalised to u in a bha aṅga (stem).,
Thus विदुषः पश्य, विदुषा, विदुषे, पेचुषः पश्य, पेचुषा, पेचुषे, ययुषः पश्य ॥ For the purposes of the elision of आ 6.4.64, vocalisation under the present sutra should not be considered as asiddha 6.4.22. Thus पा + क्वसु 3.2.107 = पपा + वस् = पपा + उस् + शस् 6.4.131, (VI. I. 108). Now if उ were to be considered as asiddha, then the affix does not begin with a vowel, and we can not apply 6.4.64, which requires the elision of आ, but the samprasarana is not considered assiddha, and we have पप् + उस् + अस् = पपुषः पश्य ॥ In the nominative, where the stem is not भ, we have पपा + वस् + स् = पपी + वस् + स 6.4.66 = पपीवान् 7.1.70, 6.4.10, 6.1.68 and 8.2.23. The affix क्वसु is included in वसु for the purposes of samprasarana.,