What is MIME type "application/x-epoc-opo"?

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

application/x-epoc-opo is the MIME type for files that contain compiled code from the OPL language. These files are used on systems running the legacy EPOC operating system.

Files of this type are created when developers compile source code written in OPL (Open Programming Language) into object modules. They help the operating system quickly execute pre-compiled routines and integrate application components.

These modules are typically stored with the file extension OPO.

They are essential for building and executing applications on devices that use the EPOC system.
They improve performance by shifting processing work from runtime to compile time.
They maintain compatibility with legacy application frameworks on older mobile and handheld devices.

Additional details on the operating system that uses these modules can be found at EPOC Operating System.

Associated file extensions

.opo

Usage Examples

HTTP Header

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


    Content-Type: application/x-epoc-opo

HTML

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


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

Associated file extensions

.opo

FAQs

What is the application/x-epoc-opo MIME type used for?

The MIME type application/x-epoc-opo represents compiled OPL (Open Programming Language) object files used by the legacy EPOC operating system. These files, which typically carry the .opo extension, contain binary code that allows applications to run on devices like the Psion Series 5.

How do I open an OPO file on Windows or macOS?

You cannot open an .opo file directly with standard text editors or modern media players because it contains compiled binary code. To run or view the content of these files, you generally need an EPOC emulator or a specific OPL decompiler designed for Psion-era software development.

What is the difference between .opl and .opo files?

An .opl file contains the human-readable source code written in the Open Programming Language, whereas an .opo file is the compiled result of that code. The application/x-epoc-opo type specifically refers to the compiled object module that the operating system executes, offering faster performance than interpreting the raw source.

How do I configure Apache to serve OPO files correctly?

To ensure browsers or download managers handle these files correctly, add the MIME type mapping to your Apache configuration or .htaccess file. Use the following directive: AddType application/x-epoc-opo .opo.

How do I configure Nginx to support application/x-epoc-opo?

For Nginx servers, you should update your mime.types file or add the configuration block within your server context. The syntax is: types { application/x-epoc-opo opo; }.

Are there security risks associated with application/x-epoc-opo files?

Yes, because these files contain executable bytecode intended for the EPOC operating system. While they cannot harm a modern Windows or Mac PC directly, they could theoretically contain malicious code if executed within an EPOC emulator or on original legacy hardware.

What does the 'x-' prefix mean in this MIME type?

The x- prefix indicates that application/x-epoc-opo is a non-standard or experimental type not officially registered with the IANA at the time of its creation. It was defined by the vendor (Symbian/Psion) for use specifically within their ecosystem.

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.