There are four segments to the ten (10) digit ISBN, with hyphens in between: Group Number (G), Publisher Number (P), Title Number (T), and Check Digit (C).
If the first digit of the ISBN is between '0' and '7' (inclusive), then G is a single digit. If the first digit is an '8', then G has two digits. If the first digit is a '9', then G may have between 2 and 5 digits. If the first two digits are '90' to '94', then G has two digits. If the first two digits are '95' to '98', then G has three digits. If the first three digits are '990' to '995' then G also has three digits. If the first three digits are '996' to '998' then G has four digits. Otherwise, G has five digits.
Group Numbers 0 and 1 are called the "English Group", and are reserved for The U.S., U.K., Canada, Australia, New Zealand, etc. The Group Agencies determine the allocation of the remaining digits between P and T.
Copyright © 2010 Gregor N. Purdy. All rights reserved.