Step 3.10: Local Bib Subject Matching
MARS 2.0 matches specified local subject fields against designated national subject authority headings. Many libraries create local subject fields in the 6XX field range with a 2nd indicator of 4, or in local 69X tags.
MARS 2.0 can attempt to match the designated subject heading against a representative national heading. If it does not find a match it will then attempt to find matches in other tags represented in the subject authority file.
Search 6xx x4 against LC
For those headings that match a heading in the LC Authority File, the 2nd indicator is changed from 4 to 0. Headings that match a cross-reference in LC are flipped to the established LC form of the heading and the 2nd indicator is again changed from 4 to 0:
original local bib heading: 650 4 $a American Civil War, 1861-1865. updated local bib headings: 650 0 $a United States $x History $x Civil War, 1861-1865.
After the matching is completed, all remaining Local subject headings (i.e., those that did not match a heading in LC) are removed from the records.
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