[zeromq-dev] [PATCH] Add msg_t::label flag

[Martin Sustrik]

Hi Fabien,

+Bit 1 (LABEL): _This message part is not part of the original
+message._ A value of 1 indicate a message part that weren't part of
+the original stream.  They are used internally by the transport to
+indicate, for example, the origin of a message.
+
+Bits 2-7: _Reserved_. Bits 1-7 are reserved for future expansion and 
MUST be
  set to zero.

It should be explained how LABEL flag interacts with MORE flag. I would 
propose something like this:

1. Labels always occur at the beginning of the message. If label appears 
elsewhere in the message, the message is malformed.

2. Labels never have MORE flags set. Combination of LAVEL and MORE on 
the same message part makes the message malformed.

Thoughts?
Martin