Appendix G - Format Changes
MARC 21 Bibliographic
May 2026
This section is provided for the lists of format changes
that accompany each update to the MARC 21 Format for
Bibliographic Data.
MARC 21 FORMAT FOR BIBLIOGRAPHIC DATA
FORMAT CHANGE LIST
Update No. 42, May 2026
This page documents the changes contained in the thirtieth
update to the 1999 edition of the MARC 21 Format for
Bibliographic Data. Update No. 42 (May 2026)
includes changes resulting from proposals that were
considered by the MARC 21 community since the publication of Update No. 41 (December 2025).
UPDATE 42 CHANGES
■ New content designators:
Indicator
2ndPresence of accessibility features/hazards in 341 (Accessibility Content)
Indicator values
#No information provided in 341 (Accessibility Content) 2nd indicator: Presence of accessibility features/hazards
1Accessibility features present in 341 (Accessibility Content) 2nd indicator: Presence of accessibility features/hazards
2No accessibility features present in 341 (Accessibility Content) 2nd indicator: Presence of accessibility features/hazards
3Sensory hazards present in 341 (Accessibility Content) 2nd indicator: Presence of accessibility features/hazards
Subfields
$h Sensory hazards (R) in 341 (Accessibility Content)
$7 Data provenance (R) in 341 (Accessibility Content)
Codes
a - Activity report
in Continuing Resources 008/21 (Type of continuing resource) (006/04)
i - Serial zine
in Continuing Resources 008/21 (Type of continuing resource) (006/04)
q - Serial podcast
in Continuing Resources 008/21 (Type of continuing resource) (006/04)
■ Changes in content designator
names and definitions:
Fields
041Language Code field definition and scope redescribed
341Accessibility Content field definition and scope redescribed
Indicator values
0Adaptive features to access primary content renamed Accessibility information related to primary content and redescribed in 341 (Accessibility Content) 1st indicator: Application
1Adaptive features to access secondary content renamed Accessibility information related to secondary content and redescribed in 341 (Accessibility Content) 1st indicator: Application
Character Position
008/35-37 - Language redescribed in 008 (All Materials)
Code
# - None of the above
redescribed in Continuing Resources 008/21 (Type of continuing resource) (006/04)
||| - No attempt to code
redescribed in All Materials 008/35-37 (Language)
■ Fast-track changes:
Subfield
$a Language code of text/sound track or separate title renamed Language code of text or sound track in 041 (Language Code)
Code
sgn - Sign languages
redescribed in All Materials 008/35-37 (Language)