[Other] Old news, still unresolved

[davidjackson]

ISBNs turned into EANs over a slightly longer period of time, so it's not quite cut and dried as a date determiner.

I was just looking at the ISBN,  not the EAN, on the back of the book (both appear, the ISBN is above the barcode; the EAN starts with 978 before repeating the ISBN number and is part of the barcode).
The International ISBN Agency You are not allowed to view links. Register or Login to view.:

An ISBN is an International Standard Book Number. ISBNs were 10 digits in length up to the end of December 2006, but since 1 January 2007 they now always consist of 13 digits.