The change to am of the Instrumental -3rd case and Locative -7th-case-affixes coming after an avyayībhāva compound that ends in a , occurs diversely.,
उपकुम्भेन or उपकुम्भम् कृतं 'done by upakumbha'; उपकुम्भे निधेहि or उपकुम्भम् निधेहि 'put it in the upakumbha.'
Vart:- The अम् substitution is invariable and not optional in the locative case when the Avyayibhava compound denotes prosperity (II. 1.6.) or a compound of rivers 2.1.20 and 2.1.21 or a compound having a numeral for its member 2.1.19; as, सुमद्रम् 'well or prosperous with the Madras'; सुमगधम् 'well or prosperous with the Magadhas'; similarly उन्मत्तगङ्गम् । लोहितगङ्गम् । एकविंशतिभारद्वाजम् । The word 'diversely' establishes all these even without the Vartika.,