By using Pose Archive you can save and load collection of poses for characters and objects.
Save New Pose
You can create new pose for selected character.
You can save poses in different categories like act, face, and lip sync.
Save Default Pose
Lets you save a new pose for default pose. You can load this pose by using Rig Reset button in main toolbar.
If you check this checkbox, poses for selected character will be update every time you select another character.