Harvest implemented a dual ISBN system in mid 2002 which asks the operator
to enter the 13 character ISBN, and then records both the 13 character and
10 character ISBN against each book product, enabling a look up feature using
either key.

As our suppliers gradually convert to using the 13 character ISBN, we will
flag each supplier accordingly. This flag will instruct the program to use
the 13 character ISBN for ordering purposes. We currently see no need to
delete the 10 character ISBN. It will no doubt be useful in the future for
enquiries on sales history.

