Note: Subfield ‡8 is defined differently in field 852, where it is used to sequence related holdings records.
Subfield ‡8 has three parts:
The linking number is required. It occurs in subfield ‡8 in all fields to be linked (fields containing the same linking number are linked).
The sequence number is optional and preceded by a period (.). It is used to indicate the order in which the linked fields display (lower sequence numbers display before higher ones). If used, it must occur in all subfields ‡8 containing the same linking number.
The field link type is required and preceded by a reverse slash (\). It is a code indicating the reason for the link and it follows the linking number (or sequence number, if present). Field link type is required except when subfield ‡8 is used to link and sequence 85x-87x holdings fields. These are the valid codes:
a (Action). Used to link one or more fields with another field to which the processing or reference actions relate. This code is typically used only when there is more than one 5xx field that relates to another 5xx field.
c (Constituent item). Used in a record for a collection or a single item consisting of identifiable constituent units, to link the fields relating to the constituent units. All other non-linked data elements in the record pertain to the collection or item as a whole.
r (Reproduction). Used in a record for a reproduction to identify fields linked because they contain information concerning only the reproduction. Other descriptive information in the record pertains to the original (with the exception of field 007 (Physical Description fixed field), fixed field Form, field 245 subfield ‡h (Title Statement / Medium), and field 533 (Reproduction Note)).
x (General sequencing). Used in a record to make a link between fields to show a sequence between them. The sequence could be one that orders the pieces of a long field that has been broken up, indicates the relative importance of fields within the sequence, or is used for some other sequencing purpose. Use of the sequence number in subfield ‡8 is required when this code is used.