What is MIME type "application/x-123"?

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

The MIME type application/x-123 is assigned to spreadsheet files created by Lotus 1-2-3 software. It signals to your system that the file holds spreadsheet data with formulas, cell styles, and structures.

This type is especially important for legacy file support. It works with older files created in different versions of the software. For example, files using the following extensions are identified by this MIME type: 123, WKS, WK1, and WK2.


For more technical details on MIME types, see the information available at MIME on Wikipedia.

Associated file extensions

.123, .wks, .wk1, .wk2

Usage Examples

HTTP Header

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


    Content-Type: application/x-123

HTML

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


    <a href="file.dat" type="application/x-123">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-123');    
      res.end('Content here');    
    }).listen(3000);

Associated file extensions

.123, .wks, .wk1, .wk2

FAQs

What software creates files with the application/x-123 MIME type?

This MIME type is primarily associated with Lotus 1-2-3, a classic spreadsheet program that was popular in the DOS and early Windows eras. It encompasses several legacy file formats, including those with .123, .wks, and .wk1 extensions.

How do I open an application/x-123 file on a modern computer?

You can usually open these files using modern spreadsheet software that maintains legacy compatibility, such as LibreOffice Calc or Corel Quattro Pro. While older versions of Microsoft Excel supported these natively, newer versions may require you to enable specific legacy file blockers or use a file converter.

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

Web browsers like Chrome, Firefox, and Edge do not have built-in engines to render Lotus 1-2-3 spreadsheets. When a server sends the application/x-123 header, the browser defaults to downloading the file so you can open it locally with a dedicated application.

How do I configure Apache to serve Lotus 1-2-3 files correctly?

To ensure browsers recognize the file type for download, add the directive to your .htaccess file or global configuration. Use the line: AddType application/x-123 .123 .wk1 .wk2 .wks.

How do I add support for this MIME type in Nginx?

You should update your mime.types file or add a types block inside your server configuration. The entry should look like this: application/x-123 123 wk1 wk2 wks; to map the extensions correctly.

Are application/x-123 files safe to open?

While generally safe, legacy spreadsheet files can theoretically contain malicious macros or binary exploits. It is always recommended to scan files downloaded from unknown sources with antivirus software before opening them in a spreadsheet application.

What does the 'x-' prefix mean in application/x-123?

The x- prefix indicates that this is a non-standard or experimental MIME type that was not originally registered with the IANA (Internet Assigned Numbers Authority). It was commonly used for proprietary formats like Lotus 1-2-3 before standard types were established.

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.