Control Serial Number: Edition 2 applies directly to all instruments.
Edition 1 : 1st May 1990 : 81536-90011 : E0590
1st December 1990 : 81536-90011 : E1290
Edition 2 : 1st April 1992 : 81536-90011 : E0492
1st March 1993 : 81536-90011 : E0393
1st December 1994 : 81536-90011 : E1294
1st July 1996 : 81536-90011 : E0796