
MARS 2.0 can flip certain fields between each other during the authority matching process. Sometimes bibliographic records have been generated with information appearing in the wrong field. With Tag Flipping turned on, these fields can be set to match against different tags regardless of the information within the original field:
Bib headings: 650 _0 $a Italy (Rome) 650 _0 $a European Union. Match as tag (flip): 651 _0 $a Italy (Rome) 610 20 $a European Union.*
*the European Union flip will only happen if the optional 650-flip is added
If the authority record causes the tag flip (difference in usage between 1XX and 4XX), then tags will always be flipped regardless of any other rule. Tag flipping rules includes X50 to X00 flipping. Old processing rules disallowed the X50 to X00 flipping, however, with the changing rules for fictitious and legendary characters, the need to allow X50 to flip to X00 was vital.
The rule that only subjects can flip to/from X50 and X51 also applies here. The MARS 2.0 Auxilliary File will not be included in this rule.
If Tag Flipping is marked, then the following rules apply:
Note: A Possible Invalid Tags report (see Step 5.2, R09) includes headings in which MARS 2.0 was programmed not to flip the tag, even though the tags in the bibliographic and authority records did match.
For example, a 130 tag is never flipped to a 100; similarly, a 710 is never allowed to flip to a 651. The Tags Flipped report (see Step 5.2, R32) includes tags that were changed during automated processing.
*Never say never in these rules, as we can also create a custom match rule that would allow these particular flips, upon request.
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