Its a measure of time, from beginning to end to beginning again.
I tend to view it as a path from http://www.gamesas.com/index.php?/topic/1084775-the-parabolic-kalpa/page__p__15807647__fromsearch__1entry15807647, though thats more a model and a theory.
This thread is http://www.gamesas.com/index.php?/topic/921446-world-eating-101/.