Since November 12, OCLC software has been adding 13-digit ISBNs in any record containing a valid 10-digit ISBN when a user adds or replaces the record. But the systematic creation of 13-digit ISBNs based on 10-digit ISBNs in all existing bibliographic records in WorldCat has not yet started. OCLC expects to generate all of these 13-digit ISBNs sometime in January 2007 and will announce their availability as the implementation date nears.