MARC Review and 'Same Tag' patterns

From the beginning (getting close to fifteen years now), MARC Review has always had this little quirk: if a review specified multiple patterns, and two or more of these patterns referenced the same tag, and this 'same tag' was a repeatable tag, then the review results would sometimes include unexpected hits.

Here is a simplistic example to illustrate:

Pattern 1: TAG=651 SUBF=a DATA=United States 
Pattern 2: TAG=651 SUBF=x DATA=History RULE=And

When this review is run, the following results were possible:

651  0$aUnited States$xEmigration and immigration$xHistory.
651  0$aNew York (N.Y.)$xEmigration and immigration$xHistory.

This happened because each pattern was evaluated separately against all occurrences of 651 in the record.

Beginning with version 232, when multiple patterns in a review reference the same tag, and the patterns are joined with the 'AND' rule, all of the patterns in question must match a single occurrence.

Thus, in the above review and example, the version 232 results will be:

651  0$aUnited States$xEmigration and immigration$xHistory.
232/sametagpatterns.txt · Last modified: 2013/04/27 09:09 (external edit)
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