CEG, linking field, $w,$x

w Record control number.
This subfield is used to include a control number in the linking field. Subfield $w may be used in any linking entry field and is repeatable. The control numbers are taken from the following fields of the related record: 001, 010, or 016. The control number should always be preceded by the MARC code of the library or system to which the control number applies. The MARC code must be enclosed in parentheses.
Record control numbers are given only when the related record appears on OCLC. More than one control number may be given, but only the LCCN and OCLC control number are required. (Exception: record control numbers are not input when the linking entry is made for a print title which preceded a later online version. See example in CCM 31.20.4.) If the related record is authenticated, the LCCN (field 010, NUC symbol DLC) must be given. The OCLC control number (field 001, NUC symbol OCoLC) is always given since links are now clickable on OCLC. The Canadiana control number (field 016, NUC symbol CaOONL) may be given but is not mandatory. When more than one control number is given in a link, the order is not prescribed.
Per recommendation from the final report submitted by the PCC Standing Committee on Automation, Task Group on Linking Entries, "Final Report" (http://www.loc.gov/catdir/pcc/archive/tglnkentr-rpt05.pdf) catalogers should record multiple linking entry numbers in linking entry fields, when known, in order to facilitate the goal of true hyperlinking. Record control numbers are given only when the related record appears on OCLC. (Exception: record control numbers are not input when the linking entry is made for a print title that preceded a later online version. See example in CCM 31.20.4.) If the related record is authenticated, the LCCN (field 010, MARC code DLC) must be given. The OCLC control number (field 001, MARC code OCoLC) is always given since OCLC control numbers in the Connexion browser are "hot linked" to retrieve related records. The Canadiana control number (field 016, MARC code CaOONL) may also given. When more than one control number is given in a link, the order is not prescribed. (Note: When OCLC runs a macro to check the structure of elements in 760-787 subfield $w's, as part of this quality control check, the (DLC) $w is placed before the (OCoLC) $w.)
1. Instructions for inputting the LCCN (from field 010 of related record).
The LCCN in subfield $w of a linking entry field corresponds to that in field 010 subfield $a of the related record; but the form input in subfield $w is not the one used in OCLC field 010. Instead, it is, approximately, the machine-readable form of the LCCN. Accordingly, there are differences in how the post-2000 and pre-2001 formats of LCCN are recorded in subfield $w. (See CEG 010 for guidelines on OCLC field 010. See Appendix P for information on formats of the machine-readable LCCN.)
Post-2000 LCCN format:
a) Always input the MARC code "DLC" enclosed within parentheses.
b) Input two leading blank spaces between the symbol "(DLC)" and the year information if the LCCN has no prefix. If the LCCN has a two-character prefix, input no blank spaces between the prefix and the year numbers.
c) Input the four-digit year information.
d) Do not input a hyphen.
e) Input the six-digit number. Input leading zeros where necessary.
776 1# $t ESAIM. Control, optimisation and calculus of variations $x 1292-8119 $w (DLC) 2001203401 $w (OCoLC)45723846
780 00 $t Greater Niles Center news $w (DLC)sn2001061303 $w (OCoLC)45762825
785 00 Public Utilities Commission of Nevada. $t Biennial report $w (OCoLC)42671476 $w (DLC) 2001202263
785 00 $t Freedom watch (Toronto, Ont.) $w (DLC)cn2001390000 $w (OCoLC)45400852
Pre-2001 LCCN format:
a) Always input the MARC code "DLC" enclosed within parentheses.
b) Input three leading blank spaces between the symbol "(DLC)" and the year numbers if the LCCN has no prefix. If the LCCN has a prefix of fewer than three characters, leave the appropriate number of blank spaces following the prefix.
c) Input the two-digit year information.
d) Do not input a hyphen.
e) Input the six-digit number. Input leading zeros where necessary.
f) Do not input trailing blank following the number. (If trailing blank is input, the OCLC system removes it.)
g) Do not input alphabetic identifiers and/or revision dates.
780 00 $t Techniques of biochemical and biophysical morphology $w (DLC) 72000153
780 00 $t Review of existential psychology & psychiatry $w (DLC)sf 77000170
780 00 $t Journal of neurosurgery $w (DLC)med47001541
785 00 $t Bread and other bakery products. $x 0575-7967 $w (DLC)ce 84079118 $w (CaOONL)840791186E
2. Instructions for inputting the Canadiana number (from field 016).
a) Input the number preceded by the MARC code "CaOONL" enclosed within parentheses.
b) Do not input any spaces between the closing parentheses and the number.
775 1# $t Décormag $g hiver 1978/79- $x 0707-1698 $w (DLC)cn 79031036 $w (CaOONL)79031068
Note: A ce-, cf-, or cn-prefixed control number in field 010 is an LCCN and is also given with NUC symbol "DLC."
3. Instructions for inputting the OCLC control number (from field 001).
a) Input the MARC code "OCoLC" enclosed within parentheses.
b) Input the OCLC control number of the related record. Leave no spaces between the symbol "(OCoLC)" and the control number.
780 00 $t Institute report (Letterman Army Institute of Research) $w (OCoLC)3067999
Linking to latest entry records (See C10)
Linking to LAC French-language records
CONSER members should not link LAC French-language cataloging records to English-language cataloging records, or vice versa. Only LAC may provide links between French-language cataloging records, or between French-language and English-language cataloging records that are authenticated by LAC only. Links to LAC French-language cataloging records will be deleted from records subsequently authenticated by LC or NSDP.
$x International Standard Serial Number.
Contains the ISSN from field 022 of the related record.
1) For U.S. or Canadian titles, the ISSN should be included only when the related record has been authenticated by NSDP or ISSN Canada.
2) For foreign titles, the ISSN should be included when it is available either in the related record or the ISSN Register.

Related record:

022 ##
130 0#
222 04

0002-2756
Airman (Washington, D.C.)
The Airman
Linking entry:

[765-787]

$t Airman (Washington, D.C.) $x 0002-2756
Do not input the term "ISSN" in subfield $x. It can be generated on output via a user's print program.
$y Coden designation.
Contains the CODEN from field 030 of the related record. Do not input the term "CODEN" in subfield $y. It can be generated on output via a user's display program.
a) Input the first five characters plus the check digit in uppercase, if available.
b) Delete any hyphen between the 4th and 5th characters.
c) Omit any spacing between characters.
780 00 $t Illinois journal of mathematics $y IJMTAW $w (DLC) 59003745
$z International Standard Book Number.
Contains the ISBN from field 020 of the related record. Do not input the term "ISBN" in subfield $z; the term may be generated on output via a user's display program.
$6 Linkage.
For instructions on the use of subfield $6, see Field 880.
$7 Control subfield.
The control subfield contains up to four, one-character codes that may include:
a) Type of main entry name given in subfield $a;
b) Form of name given in subfield $a;
c) The type of bibliographic record from Leader/06 of the related record, and;
d) The bibliographic level from Leader/07 of the related record.
Subfield $7 is an optional subfield and is not currently used for CONSER input.
Special instructions–Numerous related records
In cases where numerous titles are related to the resource, each cataloged separately, it may be impractical to list each in a separate linking field. When this occurs, the following method may be applied.
a) Create a 580 note providing an explanation of the related titles associated with the resource.
b) If each related title has the same common title, give the common title in the linking field. Use the mark of omission for the section title. Add the LC control number (or the OCLC control if there is no LC number) of each related title in separate subfields $w.
c) If the related titles do not have a common title, give as much information as possible in the 580 field and omit the linking fields.
245 00 World agriculture outlook & situation.
580 ## Vols. for 1982- have numerous supplements covering various geographic world areas: Western Europe, Eastern Europe, USSR, Asia, South Asia, China, Middle East and North Africa, Sub-Saharan Africa, Western Hemisphere, North America and Oceania, Latin America, etc. Supplements have common title: Review of agriculture in … and outlook for …, 1982; World agriculture regional supplement, 1983-
770 1# $t Review of agriculture in … and outlook for … $w (DLC) 82645567 $w (DLC) 83641501 $w (DLC) 84644070 $w (DLC)sc 83002053 $w (DLC) 83641487 $w (DLC)sc 83007067 $w (DLC) 8347862 $w (OCoLC)9476625
770 1# $t World agriculture regional supplement … $w (DLC) 84644204 $w (DLC) 84642744 $w (DLC) 84644205 $w (DLC) 83647919 $w (DLC) 84642701 $w (OCoLC)10196053 $w (OCoLC)10191180 $w (OCoLC)10216626 $w (OCoLC)6559094

$x International Standard Serial Number.
Contains the ISSN from field 022 of the related record.
1) For U.S. or Canadian titles, the ISSN should be included only when the related record has been authenticated by NSDP or ISSN Canada.
2) For foreign titles, the ISSN should be included when it is available either in the related record or the ISSN Register.

Related record:

022 ##
130 0#
222 04

0002-2756
Airman (Washington, D.C.)
The Airman
Linking entry:

[765-787]

$t Airman (Washington, D.C.) $x 0002-2756
Do not input the term "ISSN" in subfield $x. It can be generated on output via a user's print program.