These codes are mainly for Louis Vuitton’s own internal use. Vintage pieces made before 1980 therefore will not have a batch code.
The first batch codes used consisted of three or four letters. These would represent the month and year of manufacture. Therefore the code 842 would have a manufacture date of February 1984.
In the late 80s Louis Vuitton added 2 alphabetic letters to reveal which factory/country had produced the item.