Until January 1, 2007, all ISBNs were allocated as 9-digit numbers followed by a
checksum character that was either a decimal digit or the letter X. A Bookland EAN was generated by concatenating the Bookland UCC 978, the 9 digits of the book's ISBN other than its checksum, and the EAN checksum digit.
Since parts of the 10-character ISBN space are nearly full, all books published from 2007 on have been allocated a 13-digit
ISBN, which is identical to the Bookland EAN. The UCC 979 has now been assigned for the expansion of Bookland,
 and was first used by publishers in the French language, which can now use the additional prefix "979-10-" in addition to the nearly full "978-2-" prefix (onto which legacy 10-character ISBNs starting with "2-" have been remapped). Books numbered with prefixes other than 978 will not be mappable to 10-character ISBNs.
The GS1 is the global identification standards organization for retail. Every country has an assigned country code which precedes the company code. The "country codes" 978 and 979 are now officially registered for allocation by the
International ISBN Agency, which maintains the official international registry of ISBN numbers allocated to book publishers.