A word ending in a case-affix is compounded with the indeclinable word prati , when meaning 'a little' and the compound so formed is called avyayībhāva,
The word नाना means a drop,' 'a little,' 'wee bit;' as, शाकप्रति \a little of vegetable,' सूपप्रति 'a little of soup.'
Why do we say 'when meaning a little'? Observe वृक्षं प्रति विद्योतते विद्युत् 'it lightens in the direction of the tree.' Here it is not compounded.
Though the word sup was, by anuvritti from sútra 2, understood in this sútra, its repetition in the text is for the purpose of indicating that the anuvritti of the word अव्यय which began with sútra 6 does not extend further into the subsequent sútra.
The word प्रतिना being exhibited in the 3rd case-affix is not an upasarjana (l.2.43) and therefore, it comes as the last member of the compound 2.2.30.,