If members are removed with this reason code, the change is because the group has split into unconnected parts which can only communicate within themselves (e.g. netsplits on IRC use this reason code).
If members are added with this reason code, the change is because unconnected parts of the group have rejoined. If this channel carries messages (e.g. Text or Tubes channels) applications must assume that the contacts being added are likely to have missed some messages as a result of the separation, and that the contacts in the group are likely to have missed some messages from the contacts being added. Note that from the added contacts' perspective, they have been in the group all along, and the contacts we indicate to be in the group (including the local user) have just rejoined the group with reason Separated. Application protocols in Tubes should be prepared to cope with this situation. The SelfHandle SHOULD NOT be removed from channels with this reason.