What is MIME type "application/x-quattro-pro"?

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-quattro-pro labels files created by the Quattro Pro spreadsheet application. It is a non‑standard type (hence the x‑ prefix) used mostly for legacy spreadsheet documents.

Quattro Pro was popular on DOS and early Windows systems. The format stores tabular data, formulas, and cell formatting in a proprietary structure. Many legacy business documents and conversion projects still rely on this format.

Format Identification: It tells systems that the file contains structured spreadsheet data.
Legacy Compatibility: It applies to various generations of Quattro Pro, from DOS versions (for example, files like WQ1, WQ2, or WKQ) to later Windows variants.
Data Handling: Applications that recognize this MIME type can process the embedded formulas and formatting for proper display and editing.

Files such as WB3, WB2, WB1, and QPW also use this designation, ensuring that a range of Quattro Pro documents is easily identified by systems and applications.

For more details on Quattro Pro and its file formats, visit Wikipedia’s Quattro Pro article.

Associated file extensions

.wb3, .wb2, .qpw, .wq1, .wb1, .wq2, .wkq

Usage Examples

HTTP Header

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


    Content-Type: application/x-quattro-pro

HTML

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


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

Associated file extensions

.wb3, .wb2, .qpw, .wq1, .wb1, .wq2, .wkq

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.