The subscription special data format is very flexible, due to the wide variety of data that is carried in this section. The way to view this data is as a linked list of ha_gs_special_block_t elements, each containing a single type of special data related to the overall subscription notification. The other fields of the subscription notification carry the normal group state value and membership information. The special data carries additional identification information for the entries listed in the group state value and membership fields. The following subscription special data items have been added: