640 SERIES DATES OF PUBLICATION AND/OR SEQUENTIAL DESIGNATION (R)
Indicators First Note format style 0 Formatted style 1 Unformatted style Second Undefined; contains a blank (^)
Subfield Codes $a Dates of publication and/or sequential designation (NR) $z Source of information (NR) $6 Linkage (NR) $8 Field link and sequence number (R)