Available in version v7+
A message that was sent as part of a group sendout, in other words, a group message. A group message is a message that is generated by a sendout to a group.
A message that was sent as part of a single message sendout, in other words, a single message sent to a single recipient. A single message is always a prepared message.
The main message of a split sendout.
A test variation sent as part of a split sendout.
A message that was sent as part of a SuperMessage to a SuperGroup.