deriv LSK ETT STT aSTA ALPH OLDHOMEPAGE NEWHOMEPAGE
The second is used for the object of a verb when the verb linksto the doer
azvam pazyAmi अश्वं पश्यामि "I see horse", here **aham अहम् is the doer
and also for adverbs (after neuter bases)
zIghran dravati शीघ्रं द्रवति "runs quickly"
See also use of cases.