Arvo Part Fratres Sheet Music Download more. ASSEMBLY CODES BY YEARS 1952 YY 1953 ZZ 1954 A 1955 B 1956 C 1957 D 1958 E 1959 F 1960 G 1961 H 1962 J 1963 K 1964 L 1965 M 1966 N 1967 P 1968 R 1969 S 1970 T 1971 U 1972 W 1973 X 1974 Y 1975 Z 1976 I 1977 O 1978 Q 1979 V 1980 A 1981 B 1982 C 1983 D 1984 E 1985 F 1986 G 1987 H 1988 I 1989 J 1990 K 1991 L 1992 M 1993 N 1994 0 1995 P 1996 Q 1997 R 1998 S 1999 T Occasionally the charact ers are weak or unevenly applied. A hand stamp is used and can be difficult to read. There are also symbols on the right side of the barrel. Proof mark is usually surrounded by an oval. The magnaflux stamp is most often a symbol inside of a triangle and usually appears to the left of the proof mark, but also may appear to the right or below it. The gallery stamp is to the right of these and may be either one or two symbols or letters. The gallery stamp(s) signify function and accuracy testing.