The following documents the changes contained in the thirty-first update to the 1999 edition of MARC 21 Format for Bibliographic Data.  Update No. 31 (December 2020) includes changes resulting from proposals that were considered by the MARC 21 community since the publication of Update No. 30 (May 2020).

New content designators:

Fields

335  Extension Plan (R)

881  Manifestation Statements (R)

Subfield codes

$c  Aspect ratio value (R) in 345 (Moving Image Characteristics)

$d  Aspect ratio designator (R) in 345 (Moving Image Characteristics)

$p  Illustrative content (R) in 340 (Physical Medium)

$0  Authority record control number or standard number (R) in 384 (Key)

$1  Real World Object URI (R) in 384 (Key)

Obsolete content designators:

Subfield codes

The following subfields were made obsolete in 856 (Electronic Location and Access):

$b  Access number (R)

$h  Processor of request (NR)

$i   Instruction (R)

$j   Bits per second (NR)

$k  Password (NR)

$l   Logon (NR)

$n  Name of location of host (NR)

$r   Settings (NR)

$t   Terminal emulation (R)

Change in content designator name and definition:

Field

345  Projection Characteristics of Moving Image renamed Moving Image Characteristics

Change in repeatability:

Field

043  Geographic Area Code changed to Repeatable (R)

See also:

Appendix G:  Format Change Lists

Appendices