Control number, assigned by any agency, of a holdings record or a related bibliographic
record for which a separate holdings record is made.
Indicators
First - Undefined
# - Undefined
Second - Undefined
# - Undefined
Subfield Codes
$a - System control number (NR)
MARC code (enclosed in parentheses) of the organization originating the system
control number, followed immediately by the number. See Organization Code
Sources for a listing of organization code sources used in MARC 21 records.
$z - Canceled or invalid control number (R)
$6 - Linkage (NR)
See the description of this subfield in Appendix A: Control Subfields.
$8 - Field link and sequence number (R)
See the description of this subfield in Appendix A: Control Subfields.