What is MIME type "image/x-cmx"?

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

The MIME type image/x-cmx identifies files using the CMX format. This format commonly stores vector-based graphics.

It signals to systems and applications that the file holds visual data meant for scalable design. The x- prefix suggests a vendor-specific or experimental type, rather than a universally standard one.

Vector Images: Stores images as scalable graphics.
Legacy Use: Often encountered in older or specialized design software.
File Recognition: Helps applications choose the right tool to open and handle the graphic data.

Additional details can be found at Filext: CMX File Extension.

Associated file extensions

.cmx

Usage Examples

HTTP Header

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


    Content-Type: image/x-cmx

HTML

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


    <a href="file.dat" type="image/x-cmx">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', 'image/x-cmx');
      res.end('Content here');
    }).listen(3000);

Associated file extensions

.cmx

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.