"In ""A Syntax for Describing Media Feature Sets""@ an expression format is presented for describing media feature capabilities using simple media feature tags. This memo defines a media feature tag whose value is a Multipurpose Internet Mail Extensions (MIME) content type. This allows the construction of feature expressions that take account of the MIME content type of the corresponding data."
RFC 2913-2000 history
2000RFC 2913-2000 MIME Content Types in Media Feature Expressions