HEAD MARKING SHALL BE RAISED OR DEPRESSED (, O10 MAX) AND ARRANGED AS FOLLOWS: MARK WITH BASIC
IUMBER (NAS OPTIONAL) EXCEPT MARK .1380-32 SIZE WITH '6' AND .1640-32 SIZE WITH '8'.
4FR. SYMBOL, LENGTH DASH NUMBER AND RECESS NUMBER ENCIRCLED, RECESS NUMBER TO BE APPROXIMATELY
5% LARGER THAN OTHER NUMBERS,