Actually, there probably isn't any. I'm serious. I think this is one of those things that the agency doesn't dare have put in writing for fear it will leak out. My suspicion is that instead it's passed on by word of mouth or other deniable means. Some people go to a demonstration in at the TSA lair in DC, they go to the regional HQs and do the demo for others, and it spreads out like a pyramid scheme.