MARC Maps

A MARC map is a systematic method for extracting library information stored in MARC records. It is a “map” to the tags and subfields in a MARC record. This “map” makes it easy for Horizon to retrieve MARC information—much like a map helps you find a geographic destination. In addition, a MARC map controls under what conditions Horizon retrieves and displays MARC data.

MARC maps are used by many fundamental processes in Horizon because you need to index, search for, and display MARC information throughout your entire Horizon system. Because MARC maps touch so many fundamental functions in Horizon, the setup of a MARC map can be a bit complex. Regardless of how you use MARC maps, you use the same logic, steps, and pattern to create each MARC map. Once you understand how to create one, you can better understand how each MARC map actually extracts the MARC data.

Each MARC map serves a specific purpose. You set up a single MARC map to extract data by specifying which tags and subfields you want Horizon to index, display, limit by, or use for bib record linking. A MARC map can extract data from a single tag or multiple tags. (For example, you can create a MARC map to extract just the main title [tag 245] for display purposes, or you can create a MARC map to extract various title tags [245, 246, 740, 780] for indexing and searching purposes.) An extraction tag is the tag you want the MARC map to “extract” or get data from.

Horizon uses MARC maps to retrieve MARC record information for these four reasons:

To index records. Horizon uses “Indexing MARC maps” to extract MARC data from specified tags and subfields and puts this data into an index table on the database. Then, when staff or users do a search, Horizon searches the index table for the MARC information.
To display MARC record information in Horizon windows. Horizon uses “Display MARC maps” to display MARC information in PAC results lists and other Horizon windows that display MARC information. (For example, when staff or borrowers search for and display a title in the Bibliographic Detail window in staff searching, Horizon uses the MARC map to “know” what MARC information to display in the window. This is because you can assign a MARC map to views that display in staff searching.)
To limit searching based on MARC data. Horizon uses “Limiting MARC maps” to limit a list of matches during searching. Staff or borrowers can “weed out” unwanted matches in a keyword search after they have started the search. (For example, if you do a title keyword search for the word “computers,” several titles may be listed. If you want only the latest information on computers, you can limit the search date by choosing “publication date” as the field option, selecting “greater than” as the limiting operator, and entering “2001” as the limiting value. Horizon regenerates the list, showing only those titles published after 2001.)
To define link tags. Horizon uses “Linking MARC maps” to control linking of bibliographic records during import. When staff imports bib records, Horizon uses a Linking MARC map along with other parameters as defined in the Import Source to determine what tags and subfields to use as match points. This process determines if your library already has an existing title in the database.

This section describes how to set up MARC maps for these four purposes. In addition, this section explains the default MARC maps that come with the Horizon system.

This section explains these topics:

 


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