For a lot of the questions I'm seeing on ELaU, it seems the answer is ultimately arbitrary and unlikely to be resolved by poll. Since style guides exist to settle the question for people who care not what sounds better, but just want to get with the program and follow a uniform convention, what manual of style should I use for technical writing for US Federal Government documents?
Well, before my question gets closed I better answer it.
U.S. Government Printing Office Style Manual is one of the better known style guides.
More recently there has been a lot of talk about plain language, and this sometimes shows up in legislation. The plain language publications tend to have a lot more about English usage.
There are agency specific guidelines, but I'll let someone more ambitious than me track them down.