Is there a sutra discussing the Pratimoksha Vows like the Bhrama Net Sutra discusses the Bodhisattva Vows?
Just a clarification on terminology, first: While we often make a distinction between sutra and vinaya, actually, the core part of the vinaya, ie. the pratimoksa, was originally called sutra, too.
But really, it is what we usually call the vinaya, which is the vibhanga, ie. exegesis, to the pratimoksa, that explains them. So, just read the basic vinaya texts, which go through all the precepts analyzing them in various ways.
I've just started going through Bhante Thanissaro's The Buddhist Monastic Code yesterday. It's available online in PDF, just google it up. (Though I'm using the printed version.) That's the Pali, as English versions from other vinayas are rather sparse on the ground.