Binary Compressed Forward Version 1

This version of the protocol is an extension to both the ASCII Basic Protocol and the Binary Compressed Forward Version 0. It is used to transfer compressed ASCII Messages or binary files.

This version is advertised in the SID Features field with the B1 and F strings (F4HOF's note: some implementations actively check against the presence of B1F, so it's strongly recommended to concatenate those flags).

The main differences with version 0 are:

An enlarged set of selective retrieval replies.
The first transmitted block is slightly changed

Commands

Selective message retrieval

Value	Alt Value	Action	Meaning
Y	+	Accept	Send the message and delete it from the queue (“Yes”)
N	-	Drop	Don't send the message and delete it from the queue (“No”)
L	=	Defer	Keep in the queue to retrieve it later
H		Hold	Send the message and hold it in the queue
R		Reject	Message is rejected
E		Error	Invalid proposal
A	!	Append	Send the message, starting from offset then delete it from the queue