History of the communication format

1970s

1974-1979

Date	Title	Content and/or notes
May 1974	OCLC-MARC Distribution Service Specifications for Magnetic Tape Containing Catalog Records for Monographs and Serials, First edition	Described processing OCLC-MARC tapes. Data set identifier: Z39.2-69MARC-OCLC. Field 049 was present in the tape record only if the institution Sent the field before entering a Produce or Update command. If no field 049 was present in the tape record, the transaction was intended for the institution's default holding library.
July 1975		Field 049 codes changed from 3 to 4 characters.
August 1975		Field 040 changed from text to 3-character code.
March 1976	OCLC-MARC Distribution Service Specifications for Magnetic Tape Containing Catalog Records for Monographs and Serials, First edition, Revision Notice No. 1	Described Leader Bytes 18 (Descriptive Cataloging Form Code) and 22 (Transaction Type Code). To accommodate Leader Byte 18, OCLC moved the Local Status Code to Byte 22 and changed its name to Transaction Type Code. OCLC also defined a new Transaction Type Code: 50 for the All Produce. These changes were effective for the weekly and biweekly tapes in March 1976 and for the monthly tapes in April 1976. A monthly tape contained records for a calendar month.
June 1976	Network Memorandum No. 11	Described additional tape service options effective July 1976. Quarterly (13 weeks) and semiannual (26 weeks) production frequencies were added. The monthly frequency changed from a calendar month to a 4-week month. The multi-institution tape option was not implemented beginning July 1976 for monthly and quarterly subscribers. For multi-institution subscribers, OCLC produced single institution tapes and charged subscribers as if they had received multi-institution tapes. This applied for the monthly tapes produced through December 19, 1976 and the quarterly tapes for July 6—October 3, 1976.
December 1976	OCLC-MARC Subscription Service Documentation, Second edition	Incorporated data for all the MARC formats. Each format was presented separately with control fields for all formats in one sequence and variable fields in another. The data set identifier was changed to: Z39.2-71MARC-OCLC.
January 1977		Changes announced in December 1976 were implemented. The multi-institution tape option was implemented for quarterly and semiannual frequencies the week ending January 2, 1977 and for monthly (4-week) frequency the week ending January 16, 1977. The first multi-institution tapes produced were for the following periods: Monthly:                   December 20, 1976—January 15, 1977 Quarterly:                 October 4—December 30, 1976 Semiannual:             July 6—December 30, 1976 All records on tape contained field 049 whether or not the field was Sent. This was a requirement for successful implementation of the multi-institution option.
May 1975 April 1978		During this period it was possible to Produce or Update with Unknown (rather than a control number) in the OCLC control number position of the fixed field display. This occurred when a user entered a reformat command immediately after saving a record with New in the control number position. The record displayed after the reformat command was no longer associated with the saved record. Unknown appeared in the control number position. (Technical Bulletin 39, May 1978). When a user entered Produce or Update on an Unknown record, the system assigned a control number to the record. The number #3741824 was the same for all records. Records were not added to the Online Union Catalog, but were recorded on the daily journal tapes and thereby selected for tape subscriptions. Field 001 appeared as ocl73741824. If you encounter ocl73741824 during processing of the tapes: The associated record probably represents Produce or Update on an Unknown since few institutions have attached their holdings to the Online Union Catalog record #3741824. A later occurrence of the number does not necessarily replace an earlier one since a different record may be associated with each numeric occurrence.
April 1978	OCLC-MARC Subscription Service Documentation, Third edition	Presented information regarding the communication format in a composite tabular form. This edition was used to process RETROARC tapes. RETOARC tape production began in September 1979 and ended in December 1980.
September 1979	Technical Bulletin 80	Described the implementation of subfields ‡l and ‡o in field 049 and field 949 for local processing of tapes.

1980s

1980

Date	Title	Content and/or notes
June 1980		Bytes 12—17 were validated in field 001 to record the date of record use (effective for records used on or after June 30, 1980). Before June 30, the date of record use was not recorded.

1981

Date	Title	Content and/or notes
January 1981	OCLC-MARC Subscription Service Documentation, Fourth edition
June 1981		The control number identifier in 001 was changed to accommodate an 8-digit OCLC Control Number. For tapes produced before June 28, 1981, the control number identifier is ocl7 in bytes 0—3. For tapes produced on and after June 28, 1981, the identifier is ocm in bytes 0—2.
July 1981	Memo and Technical Bulletin 107
August 1981	Memo and Technical Bulletins 108 and 109
August 1981		Field 007 changed. Before this date field 007 was valid for only audiovisual materials. After August 30, 1981, the generic tree 007 was valid in all formats.
October 1981	OCLC-MARC Subscription Service Documentation, Fourth edition, Revision Notice No. 1	Incorporated the changes announced in Technical Bulletins 107, 108, 109, and 112. (Technical Bulletin 112 was not distributed specifically to OCLC-MARC tape subscribers.) A replacement page for the field 001 change was included.
December 1981	OCLC-MARC Subscription Service Documentation, Fourth edition, Revision Notice No. 2	Incorporated the changes announced in Revision Notice No. 1.

1982

Date	Title	Content and/or notes
1982		During 1982, field 010 (subfield ‡z) was copied to tape incorrectly. This occurred when there was a subfield ‡z but no subfield ‡a. The data from subfield ‡z could not be reconstructed from data on the tape.
March 1982	OCLC-MARC Subscription Service Documentation, Fourth edition, Revision Notice No. 3	Incorporated the changes announced in Technical Bulletin 115, Revised.
October 1982	OCLC-MARC Subscription Service Documentation, Fourth edition, Revision Notice No. 4	Described changes based on Update 4 (September 1981) to MARC Formats for Bibliographic Data. Appendixes G and H were issued.

1983

Date	Title	Content and/or notes
April 1983	OCLC-MARC Subscription Service Documentation, Fourth edition, Revision Notice No. 5	Described the movement of the date of latest transaction from field 001 to new field 005.
June 1983		The date of the latest transaction moved from field 001 to field 005. This change affected all tapes produced after June 26, 1983.
December 1983	OCLC-MARC Subscription Service Documentation, Fourth edition, Revision Notice No. 6	Described changes based on Updates 5, 6, and 7 to MARC Formats for Bibliographic Data and in Revision Notice No. 5.

1984

Date	Title	Content and/or notes
March 1984	OCLC-MARC Subscription Service Documentation, Fourth edition, Revision Notice No. 7	Described changes based on Update 8 to MARC Formats for Bibliographic Data.
September 1984	OCLC-MARC Tape Format, Fifth edition	Name change resulted from the inclusion of Serials Union List tapes. Described changes to the machine-readable data files format (renamed computer files) and to the manuscripts format (renamed archive and manuscript control).

1985

Date	Title	Content and/or notes
April 1985	OCLC-MARC Tape Format, Fifth edition, Revision No. 1	Described changes to developing holdings tape alterations.
April 1985		Codes invalidated in September 1984 were deleted.
July 1985	Tape Format Change Notice No. 1	New series produced designed to describe changes to be made to Tape Format. Described changes based on Updates 9, 10, and 11 to MARC Formats for Bibliographic Data.
September 1985		Changes announced in July 1985 were implemented. Invalid codes were not deleted.
October 1985		Codes invalidated in September 1985 were deleted.
November 1985	OCLC-MARC Tape Format, Fifth edition, Revision No. 2	Incorporated changes announced in Tape Format Change Notice No. 1.

1986

Date	Title	Content and/or notes
February 1986	Tape Format Change Notice No. 2	Described Chinese, Japanese, and Korean (OCLC CJK350) characters on tapes. CJK characters appear in the new field 880 that is linked to other fields by the new subfield ‡6.
May 1986		The first records containing Chinese, Japanese, and Korean characters in the CJK350 character set were entered into the Online Union Catalog. The CJK350 character set is described.
June 1986	Tape Format Change Notice No. 3	Described changes based on Update 12 to MARC Formats for Bibliographic Data.
July 1986		Changes announced in June 1986 were implemented. Some invalidated codes were deleted.
September 1986	OCLC-MARC Tape Format, Fifth edition, Revision No. 3	Described changes announced in Tape Format Change Notices Nos. 2 and 3 and based on Update No. 13 to MARC Formats for Bibliographic Data.
December 1986		The first indicator value 0 in field 520 was validated in all formats. Field 850 was made valid for Books, Audiovisual Media, Archive and Manuscripts Control, Scores, Recordings, and Computer Files. OCLC made the fields valid before their announcement to accommodate records coming to OCLC on tape. The changes were later announced in Tape Format Change Notice No. 4.
December 1986 April 1987		Between December 1986 and April 1987, field 850 may appear in tapes for non-serial records. For tapes created outside that period and for all serial records, field 850 appears only on tapes sent to the Library of Congress.

1987

Date	Title	Content and/or notes
December 1986 April 1987		Between December 1986 and April 1987, field 850 may appear in tapes for non-serial records. For tapes created outside that period and for all serial records, field 850 appears only on tapes sent to the Library of Congress.
February 1987	Tape Format Change Notice No. 4	Described changes based on Update 14 to MARC Formats for Bibliographic Data.
April 1987		Changes announced in February 1987 were implemented. No invalidated codes were deleted.

1988

Date	Title	Content and/or notes
March 1988	Tape Format Change Notice No. 5	Described changes based on Update 15 to MARC Formats for Bibliographic Data.
April 1988		Changes announced in March 1988 were implemented.
October 1988	Tape Format Change Notice No. 6	Described changes based on USMARC Format for Bibliographic Data: Including Guidelines for Content Designation.
November 1988	Tape Format Change Notice No. 7	Described changes based on a subject heading correction project.
December 1988		Changes announced in October and November 1988 were implemented.

1989

Date	Title	Content and/or notes
March 1989	Tape Format Change Notice No. 8	Described changes based on Update 1 to USMARC Format for Bibliographic Data: Including Guidelines for Content Designation.
June 1989		Changes announced in March 1989 were implemented.
July 1989	OCLC-MARC Tape Format, Second edition	Incorporated changes announced in Tape Format Change Notices Nos. 4—7 and in several Technical Bulletins.
December 1989	OCLC-MARC Tape Format, Second edition, Revision No. 1	Incorporated changes announced in Tape Format Change Notice No. 8.

1990s

1990

Date	Title	Content and/or notes
April 1990	Tape Format Change Notice No. 9	Described changes based on Update 2 to USMARC Format for Bibliographic Data: Including Guidelines for Content Designation.
June 1990		Changes announced in April 1990 were implemented.
November 1990	OCLC-MARC Tape and Export Record Formats	Name change. Incorporated changes announced in Tape Format Change Notice No. 9 and information regarding Authority Data.

1991

Date	Title	Content and/or notes
June 1991	Tape and Export Record Formats Change Notice No. 1	Described changes based on Update 3 to USMARC Format for Bibliographic Data: Including Guidelines for Content Designation.
September 1991		Changes announced in June 1991 were implemented.

1992

Date	Title	Content and/or notes
July 1992	Tape and Export Record Formats Change Notice No. 2	Described changes based on Updates 4 to USMARC Format for Bibliographic Data: Including Guidelines for Content Designation and USMARC Format for Authority Data.
October 1992		Changes announced in July 1992 were implemented.

1993

Date	Title	Content and/or notes
November 1993	OCLC-MARC Tape and Export Formats, Revision 1	Incorporated changes announced in Tape and Export Record Formats Change Notice Nos. 1 and 2.

1994

Date	Title	Content and/or notes
October 1994	Tap and Export Record Formats Change Notice No. 3	Described changes pertinent to the implementation of PromptCat.
November 1994	Tap and Export Record Formats Change Notice No. 4	Described changes in OCLC-MARC tape and record formats pertinent to the implementation of Format Integration Phase 1.

1995

Date	Title	Content and/or notes
January 1995		Changes announced in November 1994 were implemented.
April 1995		Changes announced in October 1994 (Tape and Export Record Formats Change Notice No. 3) were implemented.
October 1995	Tap and Export Record Formats Change Notice No. 5	Described Harvard database record specifications.
November 1995		Changes announced in October 1995 were implemented.

1996

Date	Title	Content and/or notes
January 1996	Tap and Export Record Formats Change Notice No. 6	Described changes in OCLC-MARC tape and record formats pertinent to the implementation of Format Integration Phase 2.
March 1996		Changes announced in January 1996 were implemented.
May 1996	Tap and Export Record Formats Change Notice No. 7	Described OCLC CatCD for Windows original bibliographic cataloging record specifications.
May 1996		Changes announced in May 1996 were implemented.

1998

Date	Title	Content and/or notes
September 1998	Tap and Export Record Formats Change Notice No. 8	Described changes based on Updates 1, 2, and 3 to USMARC Format for Bibliographic Data.
October 1998		Changes announced in September 1998were implemented.

1999

Date	Title	Content and/or notes
May 1999	Tap and Export Record Formats Change Notice No. 9	Described changes in OCLC bibliographic records pertinent to the implementation of field 994.
June 1999		Changes announced in May 1999 were implemented.

2000s

2000

Date	Title	Content and/or notes
January 2000		Tape and Export Record Formats Change Notice Series discontinued.
March 2000	Technical Bulletin 236	Described changes based on Updates 1, 2, and 3 to USMARC Format for Bibliographic Data, MARC 21 Format for Bibliographic Data, and USMARC Code List documents.
April, May, and December 2000		Changes announced in March 2000 were implemented.
May 2000	Technical Bulletin 238	Described the OCLC Arabic Cataloging Pilot project and the addition of Arabic data to records in WorldCat (the OCLC Online Union Catalog).
June 2000		Changes announced in May 2000 were implemented.
June 2000	Technical Bulletin 239	Described how the implementation of the Cooperative Online Resource Catalog (CORC) affects the OCLC Cataloging service, OCLC-MARC records, and other OCLC services.
July 2000		Changes announced in June 2000 were implemented.
August 2000	Technical Bulletin 237	Described the coding change for multiple-surname headings as a result of changes to MARC 21 Format for Bibliographic Data and USMARC Format for Authority Data.  Note: Bibliographic records in WorldCat were corrected through database scans completed in April 2000. Authority records were corrected in the first half of 2000.
August 2000	Technical Bulletin 240	Described the OCLC conversion of transliterated Chinese characters in OCLC-MARC records from the Wade-Giles to the pinyin system. Also defined the conversion markers for bibliographic records (field 987, Local Romanization/Conversion History) and for authority records (field 008/07, Romanization scheme).
August, September, and October 2000		Changes announced in August 2000 were implemented.
November 2000	Technical Bulletin 241	Described the changes to the national library control number and the effects on OCLC products and services.
December 2000		Changes announced in November 2000 were implemented.

2001

Date	Title	Content and/or notes
July 2001	Technical Bulletin 244	Described changes based on Update 1 to MARC 21 Format for Bibliographic Data, Update 1 to MARC 21 Format for Holdings Data, Update 1 to MARC 21 Format for Authority Data, and MARC Code List documents.
August 2001		Changes announced in July 2001 were implemented.

2002

Date	Title	Content and/or notes
November 2002	Technical Bulletin 247	Described changes based on Update 2 to MARC 21 Format for Bibliographic Data, MARC 21 Bibliographic and Authority New Data Elements Technical Notice, and MARC Code List Technical Notices and Updates.
December 2002		Changes announced in November 2002 were implemented.
December 2002		Incorporated tape cartridge specifications into Chapter 6.

2003

Date	Title	Content and/or notes
April 2003	Technical Bulletin 249	Described changes based on Update 3 to MARC 21 Format for Bibliographic Data, Update 3 to MARC 21 Format for Authority Data, and MARC Code List Technical Notices.
May 2003		Changes announced in April 2003 were implemented.

2006

Date	Title	Content and/or notes
May 2006	Technical Bulletin 252	Described changes based on Updates 2, 3, 4, and 5 to MARC 21 Format for Bibliographic Data, Updates 4 and 5 to MARC 21 Format for Authority Data, and MARC Code List Technical Notices.
June 2006		Changes announced in May 2006 were implemented.
September 2006	Technical Bulletin 253	Described expansion of ISBN from ten to thirteen digits, the expansion of the OCLC number from eight to nine digits, and a change to the 007 field.
November 2006		Changes announced in September 2006 were implemented.

2007

Date	Title	Content and/or notes
May 2007	Technical Bulletin 254	Described changes based on Update 6 to MARC 21 Format for Bibliographic Dataand MARC Code List Technical Notices, the changes needed to integrate the RLG Union Catalog into WorldCat, especially institution records, and other changes.
May 2007		Changes announced in May 2007 were implemented.

2008

Date	Title	Content and/or notes
May 2008	Technical Bulletin 255	Described changes based on Update 7 to MARC 21 Format for Bibliographic Data, Update 7 to MARC 21 Format for Authority Data, Update 7 to MARC 21 Format for Holdings Data, changes derived from ISO 639 Joint Advisory Committee announcements, and MARC Code List Technical Notices.
June 2008		Changes announced in May 2008 were implemented.
July 2008	Technical Bulletin 256	Describes the OCLC guidelines for abbreviated-level (encoding-level 3) records.
July 2008		Changes announced in July 2008 were implemented.

2009

Date	Title	Content and/or notes
July 2009	Technical Bulletin 257	Describes changes based on Updates 8 and 9 to MARC 21 Format for Bibliographic Data, Updates 8 and 9 to MARC 21 Format for Authority Data, Updates 8 and 9 to MARC 21 Format for Holdings Data, changes derived from ISO 169 Joint Advisory Committee announcements, and MARC Code List Technical Notices.
July 2009		Changes announced in July 2009 were implemented.

2010

Date	Title	Content and/or notes
May 2010	Technical Bulletin 258	Describes changes based on Updates 10 and 11 to MARC 21 Format for Bibliographic Data, Updates 10 and 11 to MARC 21 Format for Authority Data, Update 10 to MARC 21 Format for Holdings Data, changes derived from ISO 169 Joint Advisory Committee announcements, and MARC Code List Technical Notices.
May 2010		Changes announced in May 2010 were implemented.

2011

Date	Title	Content and/or notes
August 2011	Technical Bulletin 260	Describes changes based on Update 12 to MARC 21 Format for Bibliographic Data, Update 12 to MARC 21 Format for Authority Data, Update 12 to MARC 21 Format for Holdings Data, and MARC Code List Technical Notices.
August 2011		Changes announced in August 2011 were implemented.

2012

Date	Title	Content and/or notes
May 2012	Technical Bulletin 261	Describes changes based on Updates 13 and 14 to MARC 21 Format for Bibliographic Data, Updates 13 and 14 to MARC 21 Format for Authority Data, Updates 13 and 14 to MARC 21 Format for Holdings Data, and MARC Code List Technical Notices.

2013

Date	Title	Content and/or notes
June 2013	Technical Bulletin 262	Describes changes based on Update 15 to MARC 21 Format for Bibliographic Data, Update 15 to MARC 21 Format for Authority Data, Update 15 to MARC 21 Format for Holdings Data, and MARC Code List Technical Notices.

2014

Date	Title	Content and/or notes
May 2014	Technical Bulletin 263	Describes changes based on Update 16 to MARC 21 Format for Bibliographic Data and MARC Code List Technical Notices.
August 2014	Technical Bulletin 264	Describes changes based on Updates 16, 17, and 18 to MARC 21 Format for Bibliographic Data, Updates 16, 17, and 18 to MARC 21 Format for Authority Data, Updates 16, 17, and 18 to MARC 21 Format for Holdings Data, and MARC Code List Technical Notices.

2015

Date	Title	Content and/or notes
July 2015	Technical Bulletin 265	Describes changes based on Updates 19 and 20 to MARC 21 Format for Bibliographic Data, Updates 19 and 20 to MARC 21 Format for Authority Data, Updates 19 and 20 to MARC 21 Format for Holdings Data, and MARC Code List Technical Notices.

2016

Date	Title	Content and/or notes
July 2016		Describes changes based on Updates 21 and 22 to MARC 21 Format for Bibliographic Data, Updates 21 and 22 to MARC 21 Format for Authority Data, Updates 21 and 22 to MARC 21 Format for Holdings Data, and MARC Code List Technical Notices.
August 2016	Technical Bulletin 266	Changes announced in July 2016 were implemented.