http://forums.wowace.com/showthread.php?t=19431
http://www.wowinterface.com/forums/showthread.php?t=40010
http://www.wowpedia.org/API_COMBAT_LOG_EVENT#Patch_4.2_Base_Parameters
http://www.wowpedia.org/RaidFlag
- 4.1:
timestamp, subevent, hideCaster, sourceGUID, sourceName, sourceFlags, destGUID, destName, destFlags
- 4.2:
timestamp, subevent, hideCaster, sourceGUID, sourceName, sourceFlags, sourceRaidFlags, destGUID, destName, destFlags, destRaidFlags
It seems that Blizzard has run out of space on the original UnitFlags, so they had to add another pair of UnitFlags parameters, and moved the Raid Target Icon Flags into there.
As to why Blizzard has to keep breaking it whenever they add a new argument,
quoting Xinhuan @ Wowace.com:
Blizzard cannot put the new argument at the end because the 10th argument onwards are vararg. Hence any change to the C_L_E_U API will always break all existing addons.