What is MIME type "chemical/x-daylight-smiles"?

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

chemical/x-daylight-smiles is a MIME type that indicates a chemical file format stored using the Simplified Molecular Input Line Entry System (SMILES) notation.
It encodes a molecule’s structure as a simple text string. This makes it easy to share and process chemical data.
Files using this format are typically named SMI or SMILES.

Main use case: It lets software efficiently read, write, and exchange molecular structures.
Used by cheminformatics tools for chemical analysis and modeling.
Serves well for database searches and data mining in chemical research.
Facilitates conversion between different chemical file formats.

Associated file extensions

.smi, .smiles

Usage Examples

HTTP Header

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


    Content-Type: chemical/x-daylight-smiles

HTML

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


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

Associated file extensions

.smi, .smiles

FAQs

How do I configure Apache to serve SMILES files?

You need to map the file extensions to the MIME type in your configuration. Add the line AddType chemical/x-daylight-smiles .smi .smiles to your .htaccess file or main Apache configuration to ensure browsers and chemical software interpret the data correctly.

Can web browsers display chemical/x-daylight-smiles files directly?

Most browsers will treat these files as plain text or prompt a download by default. To visualize the chemical structure directly in a webpage, you must use a JavaScript library like SmilesDrawer or JSmol to parse the chemical/x-daylight-smiles content and render it as a 2D or 3D model.

How do I set up Nginx to handle .smi files?

Update your mime.types file or the specific server block configuration. Add the entry chemical/x-daylight-smiles smi smiles; to the types block, then reload Nginx to prevent the server from sending these files as generic application/octet-stream.

What is the difference between .smi and .smiles extensions?

There is no functional difference; both extensions contain the same SMILES text string format. While .smi is the traditional 3-letter extension often used on older systems, .smiles is more descriptive. Both should be served with the chemical/x-daylight-smiles MIME type.

Why does this MIME type include 'x-daylight'?

The x- prefix indicates a non-standard or private subtype, and Daylight refers to Daylight Chemical Information Systems, the company that originally developed the SMILES specification. While widely used in cheminformatics, it reflects the format's proprietary origins rather than an IANA standard.

How can I view the raw content of a chemical/x-daylight-smiles file?

Since the SMILES format is based on ASCII characters, you can open these files in any standard text editor like Notepad or TextEdit. However, to see the visual chemical structure, you need specialized software like OpenBabel or ChemDraw.

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.