First indicator:

0  National Library of Medicine Unique ID

1  National Library of Medicine serial control number

2  Reserved for other systems



Second indicator:

#  Undefined


a  Control number (R)


Cataloging records for serials held by the National Library of Medicine may be found in LOCATORplus, NLM's online bibliographic databases.  LOCATORplus contains records for all publications which are on order, in process, or in the NLM collection.  An NLM Unique ID citation number and an NLM serial record control number may be entered in field 069.  NLM Unique Identifiers are assigned to NLM records by its online cataloging system.  NLM serial record control numbers are unique identifiers that were assigned to serials entered in the NLM online systems prior to 1999; serial records entered later do not have serial record control numbers.

OCLC discontinued use of field 069 and shifted its functions to field 016, because the latter is MARC-compatible.  Other system control numbers carried in 069 fields were copied into 016 fields, and the 069 fields were deleted from all the records in the OCLC database.  Many of the same control numbers carried in 069 and 016 fields have also been stored in OCLC-defined field 029.

First indicator

The first indicator specifies whether the control number is an NLM Unique ID number or a  serial record control number.  Value "0" is used for an NLM Unique ID, and value "1" is used for a serial record control number.

069 0# 8031364

069 0# 100955112

069 1# SR0054321

Editing Instructions

Participants may add NLM Unique ID numbers or serial record control numbers when found in NLM's online catalog, LOCATORplus, which may be accessed via the Internet (  In LOCATORplus the NLM Unique ID is labeled as such.  The serial record control number, if there is one, is labeled "Other ID Numbers" and is preceded by the letters, in parentheses, (DNLM) and followed by the letter, in parentheses, (s).  Only the characters between the parentheses constitute the serial record control number.


LC distributes the 069 field as an 035 field.  See field 035 for information on distribution.

Related fields, etc.

016, 029, 035

See also:

01X-09X  Numbers and Codes

Variable Data Fields

Section E.  MARC 21 Format for Serials as Applied Within CONSER

CONSER Editing Guide:  Contents