What is MIME type "chemical/x-cdxml"?

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

chemical/x-cdxml is a MIME type for files that store chemical structure data in an XML format.
It marks documents saved as CDXML.
The format uses XML to organize data about atoms, bonds, and other chemical properties. This structured approach makes it easy for software to read, edit, and exchange chemical information.

Chemical structure representation: Stores detailed representations of molecules and reactions.
Data portability: Supports seamless data exchange between different chemical drawing and analysis tools.
Interoperability: The XML-based design allows the file format to integrate with various databases and applications.

Its flexibility and clear, text-based format help professionals and researchers work efficiently with complex chemical data.
For more details on chemical file formats, visit resources like this guide on CDXML.

Associated file extensions

.cdxml

Usage Examples

HTTP Header

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


    Content-Type: chemical/x-cdxml

HTML

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


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

Associated file extensions

.cdxml

FAQs

What application is required to open chemical/x-cdxml files?

The primary application for this MIME type is PerkinElmer ChemDraw, the industry standard for chemical drawing. However, because the format is XML-based, other cheminformatics tools like ChemDoodle or even standard text editors can read and parse the data structure.

How do I configure my web server to serve .cdxml files correctly?

To ensure browsers recognize the file type, you must update your MIME configuration. For Apache, add AddType chemical/x-cdxml .cdxml to your .htaccess or config file. For Nginx, add chemical/x-cdxml cdxml; inside your types { ... } block.

Why doesn't my browser display the chemical structure directly?

Standard web browsers (Chrome, Firefox, Edge) do not have native rendering engines for chemical structures. Without a specific browser plugin or a JavaScript library (like ChemDoodle Web Components) embedded in the page to parse the CDXML, the browser will likely treat the file as a download or display raw XML code.

What is the difference between chemical/x-cdxml and chemical/x-cdx?

chemical/x-cdxml represents the .cdxml format, which is XML-based and human-readable. In contrast, chemical/x-cdx is used for the older, binary .cdx format. The XML version is generally preferred for web applications and data exchange due to its interoperability.

Is the chemical/x-cdxml format human-readable?

Yes, unlike binary chemical formats, chemical/x-cdxml is based on XML. This means you can open the file in a code editor (like VS Code or Notepad++) to inspect the tags defining atoms, bonds, and properties, making it easier to debug or process programmatically.

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

The x- prefix signifies that chemical/x-cdxml is a non-standard or extension subtype, rather than one officially standardized by IANA. Despite this, it is the widely accepted convention for serving ChemDraw XML files on the internet.

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.