Introducing Tuesday Tags

During 2024 the NH State Library will be running a series of blog posts here on NHAIS Notes to offer a refresher on the many MARC tags that appear in our cataloging records. We will publish these posts each Tuesday morning and each will discuss a single MARC tag. At the end of every month there will be an online 5-question self-check that you are invited to use to check your knowledge of the material covered to that point.  

We have identified 35+ tags that we plan to write about between now and the end of 2024. If you have a MARC tag that you are especially interested in email mary.a.russell@dncr.nh.gov and we will make sure it is on the list.

 Before we begin I want to define a few terms that will come up repeatedly throughout the series.

• OCLC Bibliographic Formats and Standards (which will be referred to as BF&S throughout this series) is the authoritative source of information on all things MARC as far as NHAIS is concerned. This is because all the records we use come from OCLC and that is their MARC documentation.
  
  
• The MARC 21 Format for Bibliographic Data (generally referred to as MARC) is a means for the representation and communication of bibliographic information. MARC stands for MAchine-Readable Cataloging, and is developed and maintained by the Library of Congress, in consultation with the MARC Advisory Committee (MAC).  There is lots of MARC documentation available from the Library of Congress, and it is an excellent resource, but because we use OCLC records exclusively, we use OCLC documentation.
  
  
• Leader. The part of a MARC record that contains data elements that primarily provide information for the processing of the record. The data elements contain numbers or coded values and are identified by relative character position. The Leader is fixed in length at 24 character positions and is the first field of a MARC record.
  
  
• Directory. The part of a MARC record that contains the tag, starting location, and length of each field within the record. The Directory is not displayed in most cataloging interfaces, but is included in all MARC records exported from OCLC (or the NHAIS System). This is information that machines need, but people don't need to see it.
  
  
• Variable fields. The part of a MARC record that contains most of the bibliographic detail. It is divided into variable control fields and variable data fields. This is the stuff you are looking at when you look at a record. What goes into each field is defined in the MARC standard and is made up of tags and subfields.
  
  
• Tag. A three-digit numeric value coded 000 through 999 used to identify a specific data field within the record. The tags are grouped numerically and give you an indication of the type of data you will find there. The groups are often described with only the first digit and then xx standing in for a value between 00 and 99. For example, the 0XX fields contain control numbers, coded information, classification, etc.
  
  
• Subfield. A textual element identified by a delimiter (a weird character that signals the start of a new subfield) and a lowercase alphabetic or numeric character. What data belongs in each subfield is defined as part of MARC.
  
  
• Indicator. The two positions that appear after the tag number. They can each contain a blank or a number 0 to 9. The meaning of these codes is defined for each individual tag. If one or both of the  indicators aren't used in a particular tag they are said to be "undefined." 

If you want a brush-up on copy cataloging in general, check out the NHAIS Copy Cataloging Refresher.