1564     int		mark;  in u_write_undo()  local
1744     mark = ++lastmark;  in u_write_undo()
1749 	if (uhp->uh_walk != mark)  in u_write_undo()
1751 	    uhp->uh_walk = mark;  in u_write_undo()
1760 	if (uhp->uh_prev.ptr != NULL && uhp->uh_prev.ptr->uh_walk != mark)  in u_write_undo()
1763 				     && uhp->uh_alt_next.ptr->uh_walk != mark)  in u_write_undo()
1766 					 && uhp->uh_next.ptr->uh_walk != mark)  in u_write_undo()
2327     int		    mark;  in undo_time()  local
2418 	mark = lastmark;  // avoid that GCC complains  in undo_time()
2436 	mark = ++lastmark;  in undo_time()
2446 	    uhp->uh_walk = mark;  in undo_time()
2490 					 && uhp->uh_prev.ptr->uh_walk != mark)  in undo_time()
2496 		    && uhp->uh_alt_next.ptr->uh_walk != mark)  in undo_time()
2503 		    && uhp->uh_next.ptr->uh_walk != mark)  in undo_time()
2564 	    if (uhp == NULL || (target > 0 && uhp->uh_walk != mark)  in undo_time()
2590 				     && uhp->uh_alt_prev.ptr->uh_walk == mark)  in undo_time()
2596 				    && last->uh_alt_next.ptr->uh_walk == mark)  in undo_time()
2621 		if (uhp->uh_walk != mark)  in undo_time()
2645 		if (uhp == NULL || uhp->uh_walk != mark)  in undo_time()
3077     int		mark;  in ex_undolist()  local
3087     mark = ++lastmark;  in ex_undolist()
3095 						      && uhp->uh_walk != mark)  in ex_undolist()
3113 	uhp->uh_walk = mark;  in ex_undolist()
3117 					 && uhp->uh_prev.ptr->uh_walk != mark)  in ex_undolist()
3126 		&& uhp->uh_alt_next.ptr->uh_walk != mark)  in ex_undolist()
3133 		&& uhp->uh_next.ptr->uh_walk != mark)  in ex_undolist()