4XX and 5XX fields on existing LC/NAF records may be added, deleted, and/or modified for various reasons, including:

deleting a 4XX/5XX field because it is no longer appropriate

modifying a 4XX/5XX field in order to reflect new information or make a correction

adding a new 4XX/5XX field because a variant form of the heading has been encountered

1.   For guidelines on how and when to add or modify 4XX/5XX fields, see:

AACR2, chapter 26

LCRIs for chapter 26

DCM, Section Z1

2.   Many modifications to 4XX/5XX fields will also necessitate the addition of 670 and/or 675 fields.

3.   When adding or adjusting 4XX/5XX fields on an authority record, remember that the whole record must be brought up-to-date.  Examine and, if necessary, adjust all 4XX/5XX fields in the record.  Code the Reference evaluation fixed field 008/29 appropriately.

4.   Do not delete or change linking references in existing authority records except in cases of conflicts that cannot be resolved by additions to the other heading.

See also:

Section II:  Additions and Changes to Authority Records