Structure of an ISBN
Each ISBN consists of 5 elements with each section separated by spaces or hyphens. Three of the five elements may be of varying length:
- Prefix element – Adopting the Prefix Element assigned to books by the EAN International, all ISBNs are currently prefixed by “978”. When ISBNs with “978” prefix are used up, the new “979”prefix will be used.
- Registration group element – this identifies the particular country, geographical region, or language area of the publisher. The Group Identifier of Taiwan is "957”, "986” or “626”.
- Registrant element – this identifies the particular publisher of a given book.
- Publication element – this identifies the particular edition and format of a specific title.
- Check digit – this is always the final single digit that mathematically validates the rest of the numbers.