Profile Guide Step 3.18
The information in this section does not pertain directly to the profile questions, but is important to your understanding of MARS 2.0 Authority Control processing.
LC Authority records are constructed so that they are naturally “self deblinding.”
Example (LC subject authority record sh 85048830) Established heading: 150 $aFishing See From cross-reference: 450 $aSport fishing See From Also cross-reference: 550 $aWildlife-related recreation
See From Cross-References
Most local systems generate a heading based on the 450 and 150 fields in the above authority record:
Example Sport fishing See Fishing
The See heading informs a patron searching for records using the entry term Sport fishing that works related to that topic can be found under the preferred term Fishing.
This record is “self deblinding” since the display Sport fishing, See Fishing is not generated unless you have works cataloged under the term Fishing.
If you have works cataloged under the term Fishing, MARS 2.0 will include the authority record above in your authority file.
If you have no works in your catalog entered under the topical subject heading Fishing, MARS 2.0 programs do not distribute the authority record for Fishing to you.
See From Also Cross-References
In addition to the See cross-reference, most local systems will also generate a See also display based on fields 550 and 150 in an authority record:
Example Wildlife-related recreation See also Fishing
The See also heading informs a patron searching for works related to Wildlife-related recreation that a search for the more general term Fishing should also be considered. The See also display helps patrons find works in your collection that may be related to the concept they are seeking. Whether your collection contains any works on the specific heading Wildlife-related recreation, the provision of the additional entry term is beneficial to the patron.
Deblinding See also cross-references would prevent the above See also display from being generated, usually by either deleting the 5XX fields from the authority records or changing the 5XX tag to a 4XX if your collection contains no works cataloged under that specific heading.
The MARS 2.0 staff does not recommend removal of 5XX fields from authority records, or converting a 5XX tag, for the following reason. The available See also reference in your library system catalog will direct the patron to the related term of Fishing found in your catalog, and if you were later to acquire works cataloged under Wildlife-related recreation, the necessary See also display would not appear, as the underlying 550 field had been removed from the authority record (or a See reference would be generated incorrectly indicating the library possessed no works on the primary heading).