OCLC Control Number expansion
WorldCat continues to grow! OCLC numbers are assigned to WorldCat bibliographic records, including Institution Records (IRs). The OCLC Control Number is anticipated to reach one billion after July 1, 2013. At that point, OCLC will increase the length of the OCLC number to accommodate a variable length number string.
What action should you take? If you use and/or store OCLC MARC bibliographic records and the OCLC Control Number, you will notice a change after July 1, 2013. You will need to check the systems at your institution that use OCLC MARC bibliographic records and the OCLC number. You may need to implement changes effective July 1, 2013, to ensure those systems will be able to successfully handle the longer OCLC number.
MARC 001 field format
|Future||"on"+10 or more digits||on1234567890 OR on1234567890123|
Note: The "on" prefix will be used for numbers that have 10 or more digits. Lower numbers will continue to use ‘ocn’ or ‘ocm’ as defined above.
Implementation details for MARC field 001
- If the number is less than 8 digits, the format is: "ocm" + the number prefixed with 0s to 8 digits plus a space at the end
- If the number is 8 digits, the format is: "ocm" + the number plus a space at the end
- If the number is 9 digits, the format IS: "ocn" + the number
- If the number is 10 or more digits, the format will be: "on" + the number
- "^" designates a space in the examples above. Spaces at the end only occur with prefix "ocm" and not for numbers with other prefixes.
- Leading zeros are only used with the prefix "ocm" as noted above. They are never used with other prefixes.
Other MARC fields
In the 035 field, the OCLC Control Number is usually stored with the prefix (OCoLC) and without the "ocm", "ocn" or "on" prefixes: (OCoLC)1234567890. Most other fields where the OCLC number may be stored, such as in the linking 7XX fields, also usually store the number with the "(OCoLC)" prefix. These fields and subfields are all variable in length and no special system changes are likely to be needed in order to accommodate the longer OCLC Control Number for those fields.
For more information
Read about OCLC Control Numbers to learn how they are created and how OCLC Batchload services give libraries the ability to match, merge, format and synchronize OCLC Control Numbers between their local systems and WorldCat. To see new OCLC Control Numbers when they are assigned, visit Watch WorldCat Grow.