descriptionMedia type typically expressed using a MIME format (see [IANA site](http://www.iana.org/assignments/media-types/media-types.xhtml) and [MDN reference](https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/MIME_types)), e.g. application/zip for a SoftwareApplication binary, audio/mpeg for .mp3 etc.
In cases where a [CreativeWork](https://schema.org/CreativeWork) has several media type representations, [encoding](https://schema.org/encoding) can be used to indicate each [MediaObject](https://schema.org/MediaObject) alongside particular [encodingFormat](https://schema.org/encodingFormat) information.
Unregistered or niche encoding and file formats can be indicated instead via the most appropriate URL, e.g. defining Web page or a Wikipedia/Wikidata entry.