This CVar is where your LFG role selection information is saved.
To have a combination of more than 1 setting, add the numbers together.
ie. Healer, DPS & Leader = 4+8+1 = 13
Changing this setting
In-game, you can open the LFG tool via hitting i, then changing your setting.
In-game, type the following
/console lfgSelectedRoles setting
You can exit wow, open your character's Config-cache.wtf file, and add the following line:
SET lfgSelectedRoles setting
Patch 3.3.0 (08-Dec-2009): Added