https://bugs.koha-community.org/bugzilla3/show_bug.cgi?id=43489
Bug ID: 43489
Summary: Thesaurus filtering should be scoped by auth_type, not
by MARC21 tag position
Initiative type: ---
Sponsorship ---
status:
Product: Koha
Version: Main
Hardware: All
OS: All
Status: NEW
Severity: normal
Priority: P5 - low
Component: MARC Authority data support
Assignee: [email protected]
Reporter: [email protected]
QA Contact: [email protected]
Depends on: 43483
Target Milestone: ---
Bug 43483 fixed the most common case of this problem (a blank/undefined
2nd indicator on a 6XX field being coerced to the literal thesaurus
value 'notdefined'). This bug tracks the more thorough underlying fix.
C4::Heading::MARC21::parse_heading decides whether to compute a
thesaurus value purely from the MARC tag position:
my $thesaurus =
$tag =~ m/6../
? _get_subject_thesaurus($field)
: undef;
That means any 6XX occurrence of a name heading (100/110/111/130 used
as 600/610/611/630) can still get a thesaurus constraint applied during
authority matching whenever indicator 2 is explicitly coded (0-7), even
after bug 43483's fix for the blank-indicator case. For example:
100 1_ $a Goddard, Giles
600 10 $a Goddard, Giles $x Criticism and interpretation
(indicator 2 = 0, i.e. lcsh explicitly coded) will still search/create
against a 'lcsh' thesaurus constraint for the 600 occurrence, while the
100 occurrence has no constraint at all. If the authority created via
the 100 field was not recorded with an explicit lcsh thesaurus, the two
can again end up as separate authority records, same symptom as bug
43483, just via a narrower path.
The real distinction is not "is this tag a 6XX" but "does this
heading's auth_type represent a controlled vocabulary term, or a named
real-world entity". MARC's indicator-2 thesaurus code exists to
disambiguate genuinely separate subject vocabularies (LCSH vs MeSH vs
Sears etc) that may define overlapping terms. It has no equivalent
meaning for personal names, corporate names, meeting names or uniform
titles: NACO name authority records are reused identically regardless
of whether the name functions as a main entry (1XX), added entry
(7XX/8XX) or subject added entry (6XX) in a given bibliographic record.
There is exactly one authority record per real-world entity, not one
per (entity, thesaurus) pair.
Suggested solution:
Replace the tag-position check in parse_heading with an auth_type
check. Introduce a small table of auth_types for which a thesaurus is a
meaningful concept - genuine subject/vocabulary terms:
TOPIC_TERM, GEOGR_NAME, CHRON_TERM, GENRE/FORM, MED_PERFRM
and only call _get_subject_thesaurus for a 6XX field whose auth_type is
in that set. Name-entity auth_types - PERSO_NAME, CORPO_NAME,
MEETI_NAME, UNIF_TITLE, NAME_EVENT - would then never get a thesaurus
constraint, in any tag position, even when indicator 2 is explicitly
coded.
This is more thorough and correct than the blank-indicator fix in bug
43483 because:
1. It closes the remaining gap: an explicitly coded thesaurus indicator
on a name-type 6XX field no longer fragments matching either, not
just the blank/undefined case.
2. It matches real cataloguing practice (NACO/LCNAF): the thesaurus
concept is a property of subject vocabularies, not of names. Scoping
by auth_type encodes that directly instead of relying on tag
position as a proxy for it.
3. It is symmetric by construction for every current and future name
auth_type, rather than requiring each edge case (blank indicator,
explicit indicator, UNIMARC vs MARC21) to be patched individually as
it is discovered, which is how bug 33277 and bug 43483 each arose.
4. Genuine subject/vocabulary auth_types (TOPIC_TERM, GEOGR_NAME,
CHRON_TERM, GENRE/FORM, MED_PERFRM) keep their existing, correct
thesaurus-scoped behaviour, so this does not reopen bug 33277 or
affect bug 39503's 6XX-to-6XX collapsing logic.
C4::Heading::UNIMARC::parse_heading already always returns thesaurus
undef, so UNIMARC is unaffected by either bug and needs no change.
Test plan:
1. Turn on LinkerConsiderThesaurus, AutoLinkBiblios and
AutoCreateAuthorities.
2. Catalogue a bibliographic record with the same personal name in a
100 field and a 600 field where indicator 2 is explicitly coded
(e.g. 0 for lcsh), with no existing matching authority.
3. Confirm only one authority record is created and used by both
fields, the same as the blank-indicator case fixed by bug 43483.
4. Confirm existing subject heading matching for TOPIC_TERM, GEOGR_NAME,
CHRON_TERM, GENRE/FORM and MED_PERFRM auth_types is unchanged
(t/db_dependent/Heading.t "_search tests").
Related bugs:
Bug 43483 -- Authority linker treats the same name heading differently
in 6XX vs 1XX/7XX. This bug depends on it and generalises its fix from
"blank indicator" to "any indicator, for name-type auth_types".
Bug 33277 -- Do not search using thesaurus when linking non 6XX
fields. The auth_type-based check keeps this behaviour for name-type
auth_types, so this is not reopened.
Bug 39503 -- Linker should always respect thesaurus with
LinkerConsiderThesaurus on. Addresses 6XX-to-6XX matching for
subject/vocabulary auth_types, unaffected by this proposal.
Bug 41714 -- MARC21 authorities thesaurus link hardcoded. Makes the
tag-to-auth_type table configurable via frameworks; the auth_type-based
thesaurus check proposed here would need to read from that
configurable mapping rather than the hardcoded one, if 41714 lands
first.
Referenced Bugs:
https://bugs.koha-community.org/bugzilla3/show_bug.cgi?id=43483
[Bug 43483] Authority linker treats the same name heading differently in 6XX vs
1XX/7XX
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