So digits 1 and 5 = year. Example 82765501: Digit1=8 (year 1978 or 2008) Digit5=5 (year 1978 or 2008?) Wait no — digit5 is also year? That's wrong — in YDDDYRRR, digit1=year decade, digit5=year unit? No — the format means first digit = last digit of year, fifth digit = also last digit of year? That's redundant.
Example: 81234567 → first digit 8 = 2008? 1978? If fifth digit=1? fails. So invalid.
Positions: 1 2 3 4 5 6 7 8 Value: Y D D D Y R R R
Example: 82765501 Digit1=8, Digit5=5 — mismatch. So example wrong. So ignore bad example.
Let me give correct Gibson example: 90123345 Digit1=9 (1979 or 1989) Digit5=9 (matches) 012 = Jan 12 345 = unit 345. Same format, but first digit and fifth digit both same number. Example: 91234567 = 2009? No — 91234567: digit1=9, digit5=6? Mismatch. So invalid.
Actually Gibson confirms: 2005-2014: YDDDYRRR where Y is last digit of year, and fifth digit is same Y. So year is 197Y, 198Y, 199Y, 200Y.