Classes can be added generically to the raid or by specifying a specialization. Based on the current composition, the right sidebars are updated and indicate the current setup. The number of raid members for each roles are indicated in the "Setup" section. However, since it is possible to add "generic" classes instead of specialized ones, (for example Priest instead of Discipline), some raid members will be counted under "undetermined" because they can adopt several roles.
The abilities summary in the right sidebars are also updated based on the raid composition. The number of abilities available for the raid are indicated in three different ways :
0 : the raid hasn't any ability of this type
1 : the raid has one (or more) ability of this type
(1) : the raid may have one (or more) ability of this type, attention is required
The numbers are updated according to the current raid.
The maybe indicator means that there is no guarantee the current raid can provide this type of ability, but under certain circumstances it could. For example, if a Druid is part of the raid, the ability "Raid Defensive Cooldown" is flagged (1) because the specilization of the Druid is not known, and only Restoration can provide this ability. So, based on the specilization the Druid will take, the raid may have or not a Raid Defensive Cooldown. If the Druid is replaced by a Restoration Druid, the indicator will transform into a 1.
The raid leader must be aware that not all maybe flags could be changed into has, some are excluding. For example, a Hunter may have an ability of type "Bloodlust" or an ability of type "Combat Resurrection", but he could only choose one, he could never have the two at once.
There are also abilities classified under multiple categories, for example the Shaman's Purify Spirit spell could remove magic and curse effects but this is a single spell. Even though this tool will show 1 Remove Magic + 1 Remove Curse, the Shaman won't be able to dispel a magic effect on a first ally and immediatly a curse effect on a second ally because this is the same spell. Statistics provided by RaidComp2 should be taken in account carefully by the raid leader.
When the mouse is moved over a class or an ability, the corresponding ability(ies) or the class(es) that can give it is respectively highlighted.
Some abilities are not baseline abilities of a specialization, some of them are talents or pet based. The raid leader must pay particular attention because even a player with the right specialization may not have chosen the right talent. They are indicated the following way :
[p] : this ability comes from a particular pet
[t] : this ability is a talent
[t&p] : this ability is a talent and comes from a particular pet
[ht] : this ability is an honor talent
[b|t] : this is a either a baseline ability or a talent