Guerlain codes hacked?

The blog raidersofthelostscent stumbled on ways to determine the age of bottles and old versions of the decryption codes Guerlain. The author warns that knows for sure, and may be wrong, but with many of his observations, I agree.
So:
Codes from 1977 to 1980 8 - 9 digit.
(Always black and white boxes)
S = 1977
V = 1978
D = 1979
M = 1980

Codes from 1981 to 1983
During this period codes six-figure, the first character is always a year, the second - a month H = January, E = February, B = March, X = April, T = May, K = June, L = July, N = August, F = September R = October, A = November, C = December.
(Always black and white boxes)
U = 1981
Z = 1982
1983 J =
Codes 1985 - 1994 years
During this period codes six-figure, the first character is always a year, the second - a month H = January, E = February, B = March, X = April, T = May, K = June, L = July, N = August, F = September R = October, A = November, C = December.
W = 1985 (example: WB 6AA 1)
P = 1986
S = 1987 (example: SA 4BC 1)
V = 1988
D = 1989

(April 1985)
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Further issues with the bar code on the box
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M = 1990 (example: MH 3AA 2)
U = 1991
Z = 1992 (Example ZX 4BB 1)
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Further issues with the green dot on the box
---------------
1993 J =
Y = 1994

(September 1990)
Codes 1995 - 2001 years
During this period, they are 5-digit.
The second figure is again a month H = January, E = February, B = March, X = April, T = May, K = June, L = July, N = August, F = September, R = October, A = November, C = December.
W = 1995
P = 1996
S = 1,997 (Example 1 SX AS)
V = 1998 (Example VR 0 VS)
D = 1999 (Example DB 0 RS)
M = 2,000 (Example 1 MH RP)
U = 2001 (Example 1 UT 0K)

(October 1998)
Codes 2002 - 2007 years
During this period, four-digit codes. The first digit of the year, followed by the letter of the first half of the alphabet (A-M)
2 = 2002 (Example 2J02)
3 = 2003
4 = 2004

(Year 2002)
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From that moment on the boxes began to print a long list of prohibited ingredients
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5 = 2005 (sample 5C01)
6 = 2006
7 = 2007
Codes from 2008
Then and now they are four-digit. The first figure - a year, then the second part of the letter of the alphabet (N-Z so as not to confuse the spirits in 2002 and 2012).
8 = 2008
9 = 2009 (example 9W02)
0 = 2010
1 = 2011 (primer1T01)
2 = 2012
3 = 2013 (example 3N01)

(Year 2012)
Also codes blog author talks about the dating of the various design options box "zigzag".
All the boxes black and white "zigzag" issued from 1967 to 1983, but if you see in the corner znachoke, then it is the end of the 70s and up to 83 years.

Spray bottle natural spray appeared in the late 70s.

On the 83rd, the boxes were produced in black and gold "zigzag" and with a variety of patterns.
Logo double letter G appeared on the boxes in 2000.

But we should always remember that the design of the boxes with different flavors are not changed at the same time and that not all scents dressed in new boxes.