What is MIME type "application/x-bentley-dgn"?

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

application/x-bentley-dgn is a MIME type for files created by Bentley MicroStation. These files usually carry the DGN extension and contain vector-based CAD drawing data.

This MIME type tells operating systems and web servers how to handle the file. It ensures that design software opens it correctly and that systems treat it as a CAD file.

Design & Drafting: Stores detailed vector drawing data used in engineering and architectural projects.
Visualization: Supports the display of complex CAD models and diagrams.
Data Exchange: Facilitates the sharing of design files across different systems in collaborative projects.

The non-standard prefix x- shows that it is a proprietary format. This type is central in projects that rely on Bentley’s tools for precise technical drawings.

For further details on Bentley’s CAD systems, visit Bentley Systems.

Associated file extensions

.dgn

Usage Examples

HTTP Header

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


    Content-Type: application/x-bentley-dgn

HTML

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


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

Associated file extensions

.dgn

FAQs

What is the purpose of the application/x-bentley-dgn MIME type?

This MIME type identifies DGN files, which are CAD designs created primarily by Bentley MicroStation. It informs the operating system and web browser that the file contains vector-based engineering or architectural data, ensuring it is handed off to the correct design software rather than being treated as plain text or a generic binary.

How do I configure a web server to serve .dgn files correctly?

To ensure browsers handle the file correctly, you must add the MIME type to your server configuration. For Apache, add AddType application/x-bentley-dgn .dgn to your .htaccess or config file. For Nginx, add application/x-bentley-dgn dgn; inside the types { } block in mime.types or nginx.conf.

Can web browsers display application/x-bentley-dgn files natively?

No, standard web browsers like Chrome, Firefox, or Edge cannot render DGN files natively. When a server sends a file with the application/x-bentley-dgn header, the browser will typically prompt the user to download the file so it can be opened in a desktop application like Bentley View or MicroStation.

What software opens files associated with this MIME type?

Files with this MIME type are best opened using Bentley MicroStation or the free Bentley View application. Other CAD software, such as Autodesk AutoCAD and various GIS tools, can often import or view these files, provided the correct file associations for the .dgn extension are set in the operating system.

Why does the MIME type start with "x-"?

The x- prefix indicates that application/x-bentley-dgn is a non-standard or proprietary MIME type. It is not officially registered in the IANA standards tree like application/pdf, but it is widely recognized by industry software to identify Bentley's specific CAD format.

Is application/x-bentley-dgn the same as the MIME type for DWG files?

No, they are distinct formats. While both are used for CAD, application/x-bentley-dgn is for Bentley's DGN format, whereas AutoCAD's format typically uses types like image/vnd.dwg or application/acad. You can learn more about the differences by checking the definition for dwg.

What happens if the Content-Type is set to application/octet-stream instead?

If a server is not configured correctly, it may serve DGN files as application/octet-stream, which is a generic binary stream. This forces a file download but prevents the browser from explicitly recognizing the file as a specific CAD document, potentially leading to issues with automatic file-opening behaviors on the client side.

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.