MIME (Multipurpose Internet Mail Extensions) 是描述消息内容类型的因特网标准。 MIME 消息能包含文本、图像、音频、视频以及其他应用程序专用的数据。 官方的 MIME 信息是由 Internet Engineering Task Force (IETF) 在下面的文档中提供的： RFC-822 Standard for ARPA Internet text messages RFC-2045 MIME Part 1: Format of Internet Message Bodies RFC-2046 MIME Part 2: Media Types RFC-2047 MIME Part 3: Header Extensions for Non-ASCII Text RFC-2048 MIME Part 4: Registration Procedures RFC-2049 MIME Part 5: Conformance Criteria and Examples

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vnd = vendor.

See wikipedia :https://en.wikipedia.org/wiki/Media_type

Types or subtypes that begin with x- are nonstandard (they are not registered with IANA). Subtypes that begin with vnd are vendor-specific. Subtypes in the personal or vanity tree begin with prs.