Step 3.4: Split Headings
bib subject heading: 650 0 $a Nurses and nursing $x Effect of managed care on. replaced by two split headings: 650 0 $a Nurses $x Effect of managed care on. 650 0 $a Nursing $x Effect of managed care on.
Subfield $a matches obsolete forms of the heading (4XX fields) in 2 authority records, sh 85093349 Nurses and sh 85093362 Nursing. If a library elected to have split headings replaced by all new headings the bibliographic heading would be replaced by the 2 headings above.
bib subject heading: 650 0 $a New communities $z Massachusetts $z Boston Region. replaced by two split headings: 650 0 $a New towns $z Massachusetts $z Boston Region. 650 0 $a Planned communities $z Massachusetts $z Boston Region.
bib subject heading: 610 20 $a Vsesoi︠u︡znai︠a︡ kommunisticheskai︠a︡ partii︠a︡ (bolʹshevikov) $x Purges. replaced by two split headings: 610 20 $a Vsesoi︠u︡znai︠a︡ kommunisticheskai︠a︡ partii︠a︡ (bolʹshevikov) (1991- ) $x Purges. 610 20 $a Vsesoi︠u︡znai︠a︡ kommunisticheskai︠a︡ partii︠a︡ (bolʹshevikov) (1925-1952) $x Purges
Subfield $a matches variant forms of the heading (4XX fields) in multiple authority records. These variant forms are added to the MARC record.
Many libraries find that patrons have difficulty distinguishing between the new variants of a split heading and often search for the concept under the incorrect term.
Therefore, most libraries choose to have all split headings inserted in the bibliographic record.
NOTE: You may opt to limit the fields affected by this heading split. For instance, if you want only 650 fields to be split, please make note in section 3-14 of the Online Profile
Split heading reports available
For libraries choosing to insert split headings into the bibliographic record, a Split Headings report is generated (see Step 5.2, R31).
If obsolete headings should be retained, a Split Headings - Headings Left Unchanged report is generated instead (see Step 5.2, R17).
When MARS 2.0 Authority Control is completed, a small number of bibliographic records may contain duplicate headings. This can occur when a heading has been updated to a form already in the bibliographic record, or when two different headings update to the same form.
MARS 2.0 resolves this by deduping all authority controlled headings to ensure that headings in your bibliographic records will be unique. MARS 2.0 deduping compares heading text character by character.
For example, a 650 field with a 2nd indicator of 0 (LC subject heading) and a 650 field with a 2nd indicator of 2 (Medical subject heading) are not considered duplicates.
If the normalized bibliographic heading does not match a normalized established heading in an authority record, the heading is unmatched. An Unmatched Primary Headings report is then generated (see Step 5.2, R07). You can use the report to make additional corrections to bibliographic headings in your local system.
MARS 2.0 also creates a brief authority record out of the unmatched heading and tries to match against the national authority database during Notification services (see Step 6 of the Planning Guide). If a match is then found a new authority record is delivered to the library (see Ongoing Services in Step 6 for more details).
Alternatively, the MARS 2.0 staff can manually review bibliographic headings which do not match an authority record. For more details about this service, please contact your MARS 2.0 project manager.
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