Foldering Favorites "Ghost" group

Ryan Morlok

I see the following in the Foldering FavoritesController:

// the client code may have created a GHOST group.
// we don't want to decrypt that id.
if (!FavoriteGroupEntity.GHOST.equals(groupId))
{
groupId = decrypt(groupId);
}
decryptedGroupIds.add(groupId);

Obviously the ghost group is a group who's id doesn't go through the normal foldering encryption process; I'm wondering if anyone has any background information on its purpose.