The index regeneration that has done so much good for MNCAT (authorizing many additional headings, correcting problems from the first index gen for v14, finally making thousands of romanized Arabic, Russian, Indic and Icelandic headings searchable) has also in a few cases gone haywire. Aleph is not sensitive to tag differences; for example, a 400 or 430 reference can match to a 150 heading, resulting in the replacement of the initial subfield(s) of a topical heading with the 100 or 130 data from the mismatched authority. Not good; but fixable.
Some of these bad heading flips were present but undetected in the v14 MNCAT. Others may have newly occured because the updated authority file included new authority records, or because the internal sequence numbers of the authority records changed. Aleph's heading checker essentially accepts the first authority guidance it encounters. Hence, in v16 Aleph may have encountered the wrong authority first, where in v14 it happened to encounter the correct authority first.
Broadly speaking, these changes fall into two types. In some cases, a 4XX reference flips all instances of an unrelated heading to match its 1XX, and there are no correct uses of the 1XX heading in MNCAT. These are relatively easy to fix using either the Correct button or an Aleph batch job. More problematic are cases where the flipped headings get merged into a larger batch of correct MNCAT headings. For example, the LC children's subject authorities simplify some LCSH headings by replacing them with a single heading, which also happens to be an LCSH heading. The LC children's subject authority combines the LCSH headings "Evolution" and "Human evolution" into the single heading "Evolution." Heading flips of this kind can be very hard to untangle.
Fortunately, LEO has been able to run a job comparing the v16 headings with their v14 counterparts and listing all those which were flipped, including each bib record number. This list will be of great aid in identifying which headings need to be corrected, and which bib records were affected in those cases where headings were incorrectly merged. LEO and TS are also working on measures to ensure that these kinds of flips will not continue to be a problem.
So, what should you do? For now, if you encounter an out-or-place heading, please report it to fixit@umn.edu . If you want to understand how things went wrong in more detail and fix a problem yourself, look for an authority record matching the base of the out-of-place heading. Check its 4XX fields--could one of them have matched the base of a more appropriate heading for the bib record? If so, that's the culprit.
Two changes are usually necessary in the authority record before the bib records can be fixed. Call up the problem authority in the Cataloging Record display. Extend the 4XX with some reasonable text (e.g., add a parenthetical qualifier) to get past a mandatory block on updating an authority with a 4XX matching another authority's 1XX; and add a UPD field to block future use of the record for updating, e.g., "UPD __ $$a NO" Once the new update status is reflected in authority link text in the UMN01 index, the bib headings can be safely corrected.
Posted by s-hear at February 3, 2005 03:49 PM