MARC tagging is variety of codes, usually called tags, indicators, and delimiters, to signal to a computer that a certain type of information is following the code so that it can format it correctly and allow proper searching.
    Listed below are the most basic fields that computers (i.e., machines) use to format bibliographic records. MARC stands for "MAchine Readable Catalog". The electronic record replaces the cards that were used before the electronic era. A few cards in the old card catalog have MARC in the lower right-hand corner meaning that there were electronic, coded versions of these records in addition to the cards. However, these days the cards are no longer needed.
    The codes allow the computer to understand how the parts of a record relate to each other in a way similar to how the lines on a tax form 1040 allow the IRS to know how you figured your tax bill, or, a more contemporary example, in a way similar to how the @ and periods format e-mail addresses and allow computers to recognize them as such.

    Note the card above for the bibliographic record The Terminal Man by Michael Crichton. Somewhere in some library, there is probably an electronic version of this bibliographic record since the card has MARC in the lower right-hand corner. However, in our library it was a card that was manually produced and there was no need for the tagging to tell the computer how to format the record and how to retrieve it with the variety of searches that are possible.
    In certain views an electronic record will also look like a "user-friendly" card like the "long" screen of another Crichton record below.

    Another "user-friendly" version appears below; however, it is no longer in the format of a card and in fact takes advantage of the flexibility that an electronic record allows.

    Generally there are two types of codes (or tags) that help a computer to format this information. They are divided into tags that show fixed fields whose information is no more than a code of a fixed length itself. The other is one that shows a variable field such as author, title, publisher's name, whose information field is as variable as the lengths of  the variety of titles, etc., in the book publishing world are. They can be seen in the staff view of this record in the online public catalog below.

    In the version above (as well as the screen that staff actually uses to edit such a record) the fixed fields occur in lines 000-008. There are some variations on how the information is presented. However, the order of the fixed fields is fairly constant even if the tag codes signalling these information fields vary slightly. What is more, not only is the order of the fixed fields fairly strict, the spacing is as well. This results in the situation that when there is no information in a fixed field, then the "blanks" are recorded as spaces, so that not only is the order the same, but the position is fixed too.
    The same record is shown from a few database systems for comparison sake. While the screens can look significantly different, the order and positions of the fields remain virtually the same on each screen. Even though the MARC tags that introduce this information may vary, the information in these fields is virtually the same from one database to another and is of no consequence. It is equivalent to replacing an old iron pipe with a plastic one which is much easier to work with. Likewise, newer database systems, even with minor variations, become easier to work.
 
 
 

Fixed fields:
    Fixed fields are more codes that allow the computer to sort records in certain ways; they also can make searching for useable records easier. The fixed fields can be quite specific and one doesn't need to know about all of them to understand how they work. Below are the most important ones. In Notis and RLIN, databases that Princeton used earlier, abbreviations of the fixed fields' names were used to introduce the information that followed. In the newest version of Voyager the abbreviations are no longer used and the name of the field is also its description. That works well for the computer and is much better for us..

Encoding level
    Encoding level refers to the quality of the cataloging that one uses for the record he or she wants to create. This is important for the Library when selecting a record from a shared pool of available records from some central database since Princeton University Library with its huge collection has much greater need for additional and accurate details than other libraries with smaller collections.

Language code
    Language code refers to the language of the item for which the record is being created..

Date of publication
    Date of publication is the year that an item was published. Probably the majority of the time, this will involve only one date, and so this year will be input into the first date of publication field. There is also a second year of publication field, and the year of the last volume of a bookset is input here. Or, if a serial ceases publication, the year of the last issue will also be input here.

    Below is the Electronic Life record again--this time from the module where staff edits such a record.

    In the image above, the 008 line, which contains quite a few fixed fields, looks like a jumbled mess. But by clicking on the 008 button, a window opens allowing one to set all of the values that are important for each line. This can be done for the others as well, although it is only the Leader button (which on the Staff view corresponded to the 000 line).

Variable fields:
    These are the fields whose lengths are as long as the title, author's name, or whatever else is in these field. These, too, are the fields that one would likely see for records in the old card format.

010 __  (Library of Congress (LC) Control number) –  Sometimes zeros are added between the year digits and serial number.
        The LC number on a card (in the lower right-hand corner) would look like 97-8346. In an electronic record it looks like        
        010 __  97008346 (with 010 __ being the code that the computer understands).
020 __  (International Standard Book Number -- ISBN) -- input without hyphens.
        1-85109-286-2 in the book and on a card is input in an electronic record as 020 __ 1851092862

     Some codes are used only for serial records as in the case below.
022 __  (International Standard Serial Number -- ISSN) is input with the hypen.
        0039-3282 is input as 022 __ 0039-3282

100 1_   Personal name main entry or
700 1_  Personal name added entry (editor, compiler, etc.)
                    First indicator:  1   surname
                                           0   forename
                      Second indicator is blank.

                      100 1_ Krug, Samuel E.
                      100 1_ Campbell-Jones, Anne,‡d1951-
                      100 0_ Edward,‡cKing of England,‡dca. 1003-1066

    Note how there are still more codes, this time shown by delimiter (‡) and a letter to alert the computer as well as the staff member that a subfield with some type of information follows it as a date.

110 1_  Corporate name main entry or
710 1_  Corporate name added entry
                      110 1_ [Place].‡b[Body]
                      110 1_United States.‡bDept. of Defense.

                      110 2_ [Body]
                      110 2_ Cato Institute.

111 2_  Conference main entry  or
711 2_  Conference added entry
                      111 2_ [Conference name]‡n([number] :‡d[date] :‡c[place])
 

245 10  Title
                      First indicator:  1 – main entry other than title
                                             0 – title main entry

                      Second indicator:  number of filing character to be skipped
                                245 14 The (skip t, h, e, and the space – start filing with the next character)
                                245 12  A (skip a and the space – start filing with the next character)

245 10 Main title : ‡bsubtitle /‡cstatement of responsibility.

246 3_ Varying form of title.

250 __ Edition statement
                      1st ed.  ;  1. ed.  ;  2nd rev. ed. ; etc.

260 __ Publication information

                    Place of publication : name of publisher, date of publication. As below:
                    London :‡bClio Press,‡c1999.

 
Combinations are possible as shown below:
London :‡bMacmillan ;‡aNew York ;‡bSt. Martins Press,‡c1998.

300 __  Pagination

This field is also used to indicate multi-vol. sets.
3 v.
v.  (volumes unknown)
This field can also be used to indicate accompanying material.
‡eBook with CD
‡eBook with CD-ROM
‡eBook with microfiche

600 10  Personal name subject entry
                    600 10  Campbell-Jones, Anne,‡d1951-
610 10  Corporate name subject entry
                    610 20  Princeton University
611 20  Conference subject entry
                    611 20  Learning Education and Training Committee meeting ‡d(August 13, 2001 :‡cPrinceton, N.J.)

650 _0  Topical term subject entry
                    650 _0  Women ‡x Education (Higher)
651 _0  Geographic name subject entry
                    651 _0  Princeton (N.J.)

440 _0  Series statement
             use ‡v  for vol. number. Do not input with parentheses.

780 10   Preceding entry (Continues…)
785 10   Succeding entry (Continued by…)
               Subfield ‡t is used for both.

780 10  ‡t Old Name of Serial
785 10  ‡t New Name of Serial

    Below is the same record in two different databases. Voyager is now the database used at Princeton and pictures of those screens appear above. However, before Voyager, Princeton used Notis, whose screen appears below. Notice how the screens, while not exactly the same, are very similar, which shows how MARC tagging pretty much allows one record to display in any library database, whose records rely on MARC tagging for display and search purposes.

    We used RLIN before Notis and that screen is similar as well. RLIN is also a shared database, so that many libraries use it at the same time. This allows us to use someone else's cataloging for our books and other materials if they are not yet cataloged by Princeton's staff. The RLIN screen appears below.

Fixed Fields:

    Fixed fields are those that usually appear along the top of  the record. The information that they contain looks as cryptic as the codes used to signal the information. However, th is information is in code form itself and is deliberately short--fixed in length--which gives the name "fixed fields". Sometimes these codes are abbreviations for the information they represent. More often, they are simply letters or numbers, which correspond to a list of choices.

Variable Fields:

    Variable fields are those that are usually below fixed fields. One MARC tag here introduces an entire line of information in the record. However, since the field is variable, if more space is needed, extra lines will also be given to the same to the same field also following the same MARC tag.

    The single digit fields (MARC tags 000 through 009) when they appear on a record are the fixed fields just appearing in a different way. Just as when the fixed fields appear above, having the codes to give these fields a set order and spacing, when the fixed fields appear as values in lines 000 to 009, the order and spacing is set for these as well.

    Compare the Staff View of the sample record above taken from the online public catalog on the web and compare it with the same Voyager record--also a Staff View--but from the actual Voyager database where records are edited. The fixed fields appear in differently in each one.

    The double digit fields (010 through 099) are the fields that contain numbers that are assigned to the book at whose record one is looking. These numbers include International Standard Book Numbers (ISBN), Library of Congress numbers, Library of Congress call numbers, other kinds of call numbers, or government document numbers. There are probably other types of numbers as well, but these are the major ones.

    The 100's (100 through 199) are the fields that indicate the main entry for a book. The main entry is given to the person, organization, or meeting that authored the book in some way.

    The 700's (700 through 799) are the fields that usually indicate the added entries for a book. If a book has only one author, then there is only one 100, or 110, or 111 field. If the book has more than one author, the remaining authors will be 700, or 710, or 711 entries.

     Above in the examples are listed occasional serial notes (780 and 785) that are also among the 700's. These are somewhat unusual and can be thought of as quirks in the patterns. The codes are actually quite complex, but these generalities work pretty well to give a good sense of the logic of the MARC tagging and how it all works together. This is a good place to mention that it is possible to have one or more entries in the 700's without having an entry in the 100's.
 

    The fist half of the 200's (200 through 249) are the fields that indicate the title entries. The primary title entry will always appear with a 245 tag. A 245 field is always required; however, like the 100's, there can never be more than one 245 field. But as it is with authors, likewise there can be more than one title which should be traced in the record. Any additional titles will usually appear in 246 fields. And like the 700's, there can be as many 246 fields as are necessary. There are other title fields in this half of the 200's, but the 245 and 246 fields are the most important ones.

    A point that is interesting is that when these records were used to generate cards (when online catalogs were somewhat experimental), a card would always be published for the main entry. If the title, the 245 field, were the main entry, the first indicator would be "0". (245 02 A title for an example.) However, if the title were NOT the main entry, the first indicator needed to be "1". (245 12 A title for an example /‡cAlfred E. Neumann). This would insure that a card would be printed for the title as well as the author.
 

    The second half of the 200's (250 through 299) are fields that indicate publishing information entries. In addition to citing the publisher of the book, these fields also show the place where the publisher is located as well as the date of publication. In addition, edition (or reprint) information is also displayed in these fields.
 

    The 300's (300 through 399) are fields that indicate physical information entries. Included in this information is the number of pages in the book, the size (height) of the book, whether the book has illustrations. If the item is not a book, but rather it is a volume in a bookset, then the number of volumes will be listed in these fields. Or, if the item is part of a serial, that will be noted, too. If the serial is still being published, then the number of volumes that will be published cannot be known at this point. However, there is usually some information to indicate publishing history and how many pieces may have been published so far. Or, if the item is a microfilm, a CD-Rom, or any of the variety of other formats possible, that information is noted too.
 

    The 500's (500 through 599) are fields that indicate notes which are important to the book or other publication, but which do not fit elsewhere.
 

    The 600's (600 through 699) are fields that indicate subject entries. They are similar to the 100's and 700's when they occur for someone or something that conceivably could be an author. Of course, there are other kinds of subject entries, too, and those tags follow their own patterns.
 

      The 400's (400 through 499) and 800's (800 through 899) are fields that indicate series title entries. Series titles are statements that appear on books that have separate titles for the books. Series titles are NOT the same as serials, such as Time magazine. A serial title is traced just like a book title in a 245 field. Series titles are very complex and great care must be taken so that a library's records remain accurate and each record treats the series title (or titles--it is possible to have more than one) in the same way. For this reason there are potentially 200 tags to choose from when tracing a series statement; nevertheless, this does not necessarily mean that all 200 tags exist as real choices. This is true for all of the other tags as well. Some tag numbers have no meaning--either for the computer or the person looking at the bibliographic record.
 

      The 900's (900 through 999) are fields the indicate information usually only of local interest. These fields are used to record statistics for the library that created the record. Occasionally call numbers will appear here, too. These can be useful for other libraries, but when input, there is no intention to observe standards useful to any other library looking at the record on a database of share records (like RLN).