Note: If you are a WMS library or using full WorldShare Collection Manager, see Matching to records in WorldCat.
Titles in the WorldCat knowledge base are matched to WorldCat records based on their associated metadata including:
The matching process first identifies all records in WorldCat that match the provided metadata and then narrows the match to a single record based on three criteria or rules:
Alternative processes
Certain collections have been matched through an alternative process. Such collections correspond to content providers who are participating in one of OCLC's cataloging services. OCLC number matches for these collections are either supplied by the content provider or merged into the WorldCat knowledge base from sources internal to OCLC. As a result, they may not follow the exact same matching process described above.
If title data does not include an OCLC number
If title data does not include an OCLC number and the knowledge base cannot add an OCLC number using its matching process, a record will not be output for that title. This can include cases where:
OCLC number coverage
If a matching OCLC number becomes available at a later date, the title will be matched and its record will be delivered automatically.
More information
For more information about matching to records in WorldCat and about requirements for full-text link display, see:
For help with missing or errant OCLC numbers, see Report errant OCLC numbers.
Note: This section is an overview of the data sync matching process. It does not cover other OCLC matching processes (e.g. ILL, knowledge base, Duplicate Detection and Resolution (DDR), etc.). It does not include all of the processing details, anomalies, and exceptions that may occur during fingerprint matching.
Inaccurate or incomplete cataloging and coding, seemingly small differences between records, and certain types of inconsistencies within a record may cause machine algorithms to act in unexpected ways. No automated matching algorithm, regardless of its sophistication, can consider and correctly interpret all of the subtleties built into a bibliographic record with the accuracy that a human cataloger can.
After bibliographic records are created, sent to OCLC, and pre-processed, they are sent to matching. Matching provides an automated way to match incoming records to a single WorldCat record so that library collections can be made part of WorldCat for efficient and effective cataloging, resource sharing, library management, research and Discovery.
There are two basic steps for matching bibliographic records:
Data elements can be single MARC fields and subfields or combinations of MARC fields and subfields. The data elements are used in both retrieving records and comparing data. Algorithms determine how data elements are constructed for retrieval and how they are used in comparing records. Matching emphasizes the primary data elements. Only in certain limited circumstances are 5XX notes used in matching.
Data elements used as the primary source of retrieval and comparison for matching include, but are not limited to, the following:
In addition, other data elements used for specific situations and formats include, but are not limited to, the following:
When matching finds more than one WorldCat record that could represent the manifestation of the incoming record, it sends the records to Resolution. Record resolution is a separate process that attempts to choose from among the incoming record and the WorldCat records the best candidate for record retention based on algorithms that include but are not limited to the source of the record (field 040 subfield $c), certain authentication codes in field 042, Encoding Level, and the number of holdings.
After Resolution selects the best record, data sync sends the record to validation and on to Final actions. Final actions include adding a WorldCat record, adding a holding, canceling a holding, replacing a record, and/or transferring additional data not already present in the WorldCat record.