Internet media type

Internet media types, or MIME types as they are commonly known (after MIME -- Multipurpose Internet Mail Extensions), are the strings such as text/plain, text/html, application/octet-stream, and image/png that one commonly encounters in Content-type headers of several internet-related protocols.

[Are there any Tcl-specific media types?]

According to Multimedia MIME Reference , there is application/x-tcl