*COMDECK NHEADER
# BLOCK HEADER AS SEEN BY NIP # 
      BASED ARRAY NHEADER P(1); 
        BEGIN 
        ITEM NHADDR       U(0,0,24) ;                    # NETWORK ADDR#
        ITEM DN           U(0,0,8);   # DESTINATION NODE #
        ITEM SN           U(0,8,8);   # SOURCE NODE # 
        ITEM CN           U(0,16,8);  # CONNECTION NUMBER # 
        ITEM NBHABH       U(0,0,24);  # DN/SN/CN                       #
        ITEM NHPRI        B(0,24,1);  # HIGH PRIORITY FLAG             #
        ITEM NHBSN        U(0,25,3);  # BLOCK SEQUENCE NUMBER          #
        ITEM BT           U(0,28,4);  # BLOCK TYPE  # 
        ITEM NHDBC        U(0,32,8);  # DATA BLOCK CLARIFIER           #
        ITEM NHACT        U(0,40,4);  # APPLICATION CHARACTER TYPE     #
        ITEM NHBT         U(0,44,4);  # BLOCK TYPE FOR BAD BLOCK       #
        ITEM CC           U(0,48,12); # CHARACTER LENGTH #
        ITEM NHWORD       U(0,0,WL);  # NETWORK BLOCK HEADER WORD      #
        ITEM NHICMDA      U(0,0,8);    # ALPHA CHARACTER FOR ICMD      #
        END 
