What is MIME type "application/marc"?

A MIME type is a string that tells browsers and other tools how to handle a particular kind of file.

application/marc is a MIME type for MARC records. MARC stands for Machine-Readable Cataloging. It encodes bibliographic data for libraries in a structured, machine-friendly format.

Main use: Exchanging catalog data between library systems.
Other uses: Organizing bibliographic metadata; supporting resource discovery; aiding digital cataloging.

Files using this MIME type are typically saved with formats like MRC, MARCX, and MARC.

For more details, see Library of Congress MARC Standards.

Associated file extensions

.mrc, .mrcx, .marc

Usage Examples

HTTP Header

When serving content with this MIME type, set the Content-Type header:


    Content-Type: application/marc

HTML

In HTML, you can specify the MIME type in various elements:


    <a href="file.dat" type="application/marc">Download file</a>

Server-side (Node.js)

Setting the Content-Type header in Node.js:


    const http = require('http');    
    
    http.createServer((req, res) => {    
      res.setHeader('Content-Type', 'application/marc');    
      res.end('Content here');    
    }).listen(3000);

Associated file extensions

.mrc, .mrcx, .marc

FAQs

What is the primary purpose of the application/marc MIME type?

This MIME type is used to transmit Machine-Readable Cataloging (MARC) records, which are the standard for bibliographic data in libraries. When a server sends a file with the header Content-Type: application/marc, it indicates the file contains binary encoded catalog data, typically found in .mrc files.

How do I open a file served as application/marc?

You cannot open these files with a standard text editor or web browser. You need specialized library software such as MarcEdit, Koha, or an Integrated Library System (ILS) to interpret and display the structured bibliographic fields correctly.

How do I configure Apache to serve .mrc files correctly?

To ensure your web server identifies these files correctly, add the MIME type definition to your .htaccess file or main configuration. Use the directive AddType application/marc .mrc .marc to map the extensions to the correct content type.

Is application/marc the same as MARCXML?

No, they represent different encodings of the same data. application/marc typically refers to the traditional binary ISO 2709 format, while MARCXML uses XML tags and is usually served as application/marcxml+xml or application/xml.

Why does my browser download the file instead of displaying it?

Web browsers do not have native rendering engines for binary MARC records. Because the browser does not recognize application/marc as a displayable format (like HTML or PDF), it defaults to downloading the file for you to open locally.

How do I set up Nginx to support MARC files?

In Nginx, you can add the type to your mime.types file or include it directly in a server or location block. Add the line application/marc mrc; inside the types { ... } block to ensure the correct headers are sent.

General FAQ

What is a MIME type?

A MIME (Multipurpose Internet Mail Extensions) type is a standard that indicates the nature and format of a document, file, or assortment of bytes. MIME types are defined and standardized in IETF's RFC 6838.

MIME types are important because they help browsers and servers understand how to process a file. When a browser receives a file from a server, it uses the MIME type to determine how to display or handle the content, whether it's an image to display, a PDF to open in a viewer, or a video to play.

MIME types consist of a type and a subtype, separated by a slash (e.g., text/html, image/jpeg, application/pdf). Some MIME types also include optional parameters.

How do I find the MIME type for a file?

You can check the file extension or use a file identification tool such as file --mime-type on the command line. Many programming languages also provide libraries to detect MIME types.

Why are multiple MIME types listed for one extension?

Different applications and historical conventions may use alternative MIME identifiers for the same kind of file. Showing them all helps ensure compatibility across systems.