100 $y is not correct on Person headers

[ahankinson]

Summary: We use $y in the 100 field for "Dates Active" but this is not valid. We need to remove it from 100 to make our records suitable for VIAF, but there is an open question about where to move it to.

Previously, this field was removed from the VIAF export, but since we don't want to maintain separate exports for the different services, we need to fix this in Muscat. And, as described below, it is anyway not correct.

The only question is where this data could be migrated to. Possibilities:

• 046, Special coded dates. Unlikely, since it would be a lot of work to make the values in $y conform to the requirements for this field.
• 100$g, Miscellaneous information. Could be migrated to, e.g., "$gDates active: [current value of $y]". However, there is a note on the page for usage of 100$g: "Subfield $g is unlikely to be used in an X00 field."
• 368$s / $t: Other Attributes of a Person. Would be a good fit, but otherwise has the same problem as 046 that there would need to be some hand-editing to split $y into the start / end date format of this field.
• 678: Other Biographical Information note field. I think this makes the most sense, but rumour has it that this is going away? People: Migrate 678 #1502 . Maybe we need to reconsider this, and reserve 678 for "Period of activity" dates?
• Anything else?

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Original error report from VIAF:

"Looking at one of the examples that you provided us with that weren’t usable, I was able to find the issue.
The subfields : $v$x$y$z in the 100 tag for personal names are not allowed.

<record>
                <leader>00000nz  a2200000nu 4500</leader>
                <controlfield tag="001">people2539</controlfield>
                <controlfield tag="003">DE633</controlfield>
                <controlfield tag="005">20240725112431.0</controlfield>
                <controlfield tag="008">161109||||||||a|||||||||||||||||||||||||</controlfield>
                <datafield ind1=" " ind2=" " tag="035">
                                <subfield code="a">(DE633)people/2539</subfield>
                </datafield>
<datafield ind1="1" ind2=" " tag="100">
                                <subfield code="a">Bach, Johann Sebastian</subfield>
                                <subfield code="d">1685-1750</subfield>
                                <subfield code="y">21.03.1685-28.07.1750</subfield>
                </datafield>

Technically, $v$x$y$z are allowed in field 100, but not in name authorities, just in subject authorities.

https://www.loc.gov/marc/authority/adx00.html

"Subfield $v is appropriate only when a form subject subdivision is added to a personal name heading to form an extended subject heading. Subfield $v is used for form terms when they function as indicated above; the terms are coded in subfield $x if they function as general subdivisions."

"Subfield $x is appropriate in the X00 fields only when a topical subject subdivision is added to a name or name/title heading to form an extended subject heading."

"Subfield $y is appropriate in the X00 fields only when a chronological subject subdivision is added to a name or name/title heading to form an extended subject heading."

"Appropriate in the X00 fields only when a geographic subject subdivision is added to a name or name/title heading to form an extended subject heading."

[xhero]

Please just let me know when a consensus is reached where the field needs to be migrated to. Also keep in mind that most probably it needs to be synch'd with a release, and we will probably need to inform BSB (reason why 678 has not yet been deleted)

[alexandermarxen]

There are currently two types of data in the $y field: Periods of activity preceded by 'fl.' https://rism.online/people/30102793 and specific life data https://rism.online/people/51037516
We want to leave the $d field as it is to maintain sortability.
I could well imagine using field 678. Before that, however, the data currently there would have to be migrated to 680 $a.
For clarity, the field should then be located where 100 $y currently is.

[xhero]

Roadmap:

• Move 678 $a to 680 $a
• Move 100 $y to 678 $y
• Rename 678 to "Other life dates"
• Move 678 to "main entry", between 100 and 042
• Drop 100 $y