By the action (bhāva) of whatsoever, the time of another action is indicated, that takes the 7th case-affix.,
This is Locative Absolute. गोषु दुह्यमानासु गतः 'the cows being milked, he went away' दुग्धास्वागतः 'and returned when they were milked'. अग्निषु हूयमानेषु गतः, हुतेष्वागतः.
Why do we say 'by the action of whatsoever'? Observe यो जटाभिः स भुक्ते. Why have we used the word 'action' twice? Witness यो भुक्ते स देवदत्तः.,