I got the spec. Thanks! It looks pretty much identical to the draft. The spec is all I really need. It's a pretty straightforward data format in UDP packets, which is relatively easy. I plan to do this in probably 3 stages. 1: receive E1.31 as unicast only 2: add multicast reception (requires hacking the Ethernet library) 3: add multi-source priority and merging features I'll post here when #1 is ready for testing. I expect that will be sometime in June 2013.