HTTP uses Internet Media Types in the Content-Type (section 14.18) and Accept (section 14.1) header fields in order to provide open and extensible data typing and type negotiation.
media-type = type "/" subtype *( ";" parameter ) type = token subtype = token
Parameters may follow the type/subtype in the form of attribute/value pairs.
parameter = attribute "=" value attribute = token value = token | quoted-string
The type, subtype, and parameter attribute names are case- insensitive. Parameter values may or may not be case-sensitive, depending on the semantics of the parameter name. Linear white space (LWS) MUST NOT be used between the type and subtype, nor between an attribute and its value. User agents that recognize the media-type MUST process (or arrange to be processed by any external applications used to process that type/subtype by the user agent) the parameters for that MIME type as described by that type/subtype definition to the and inform the user of any problems discovered.
Media-type values are registered with the Internet Assigned Number Authority (IANA). The media type registration process is outlined in RFC 2048 . Use of non-registered media types is discouraged.