Fires when the raid roster changes. This occurs when a raid is formed or disbanded, if members join or leave or are moved between raid subgroups, if the loot policy or loot master is changed, or if raid leader, assistant, main tank or main assist attributes are changed.
Quite a bit of
RAID_ROSTER_UPDATE's pre-MoP functionality was moved to the new event
GROUP_ROSTER_UPDATE. Further testing is required to determine the extend of the transition.