PI is the pitch, serving to adjust all forms of knowledge into their perfect order, (one tablet gives it as two opposed and equal triangles forming a capital M. I don't know if that is significant.)
RI is the symbol of a bird, a very important bird, a dividing line, and the collector, the gatherer-together,
IG is the symbol of the door and can mean ‘to open’ and ‘to guard.
PIRIG is the symbol of the lioness’s head, her mouth open. She dates to (at least) the earliest Uruk period of 3350-3200 BC and a translation of her three symbols tells us that she is the guardian of the perimeter of the pyramid but perhaps also the means of entering it. The origins are confirmed by the ancient lexical lists. I’ve written most of the above in previous posts somewhere or other but it seems timely to re-post it here.