Packet 0x8000
Packet 0x8000: "special hold notify"
pre: OTHER
post: OTHER
A special packet that is handled specially.
The "is the packet complete" logic will read its given length, but the "skip packet" will only skip 4 bytes, thus allowing transactions. I'm still not entirely convinced that this is a good idea - perhaps explicit 'being transaction buffer' and 'end transaction buffer' packets? Allow nesting?
