This structure represents a doubly-linked list.
First node
Referenced by alloc_linked_list(), append_list_node(), decode_refinement_pass(), decode_sorting_pass(), encode_refinement_pass(), encode_sorting_pass(), free_linked_list(), insert_before_list_node(), prepend_list_node(), and remove_list_node_link().
Last node
Referenced by alloc_linked_list(), append_list_node(), insert_after_list_node(), prepend_list_node(), and remove_list_node_link().