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

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

application/x-elc is a MIME type for files containing compiled Emacs Lisp code. These files are created when Emacs converts human-readable Lisp source into bytecode for faster execution. The files use the file extension ELC.

Compiled bytecode is not meant for manual editing. It is loaded directly by Emacs to speed up processing of Lisp functions and configurations.

Performance: Bytecode runs faster than plain-text Lisp code.
Emacs Integration: These files help Emacs load and run configurations and extensions efficiently.
Specific Use: The format is tailored for the Emacs environment and is rarely used elsewhere.

The prefix x- signals that the MIME type is non-standard and specialized. For more details on how Emacs uses compiled Lisp, visit Emacs’ official site or check related entries on Wikipedia.

Associated file extensions

.elc

Usage Examples

HTTP Header

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


    Content-Type: application/x-elc

HTML

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


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

Associated file extensions

.elc

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.