Does an .A78 Header Document Exist?

As the title says.  I spent about an hour looking around on the innertubes for an .A78 header document and didn't find much.  Google only returned 7 hits which weren't terribly useful, and I even downloaded the source to Dan Boris' emulator (he apparently came up with .A78) but it has no documents about the header format in there either.

I can reverse engineer the ROM loader in the emulator I guess as a last-ditch effort but was hoping a document exists about it.  Thanks for any help in advance!