The ISBN Prefix is the publisher's language-speaking country identifier plus the publisher number of the ISBN (International Standard Book Number).
For example, the ISBN Prefix for Harlequin is 0-373 - with the 0 for a publisher of an English-speaking country and the publisher number 373. Thus the titles published by Harlequin in Spanish have the 0 as a language-speaking country identifier.
Some language-speaking country identifiers:
- 0 - English
- 1 - English
- 2 - French
- 3 - German
- 4 - Japanese
- 5 - Russian
- 7 - Chinese
- 8 + second digit - Spanish (84), Portuguese (85) and Italian (88)
The national ISBN agency assigns the publisher number and publishers receive blocks of ISBNs, with larger blocks allotted to publishers expecting to need them. Once that block of ISBNs is used, the publisher may receive another block of ISBNs, with a different publisher number. Consequently, a publisher may have different allotted publisher numbers.