[clipboard] Add RTF to the "mandatory data types" list?

Would it be possible to add RTF (MIME type of "application/rtf") [1] to the
"mandatory data types" [2] list?

While it is a proprietary file format held by Microsoft, it also has public
specs [3][4] and is designed for cross-platform interchange of text and
graphics.

More importantly, I speculate that it is one of the top three types of text
formats that people copy-and-paste: plain text, RTF, and HTML. It is also
supported, or at least readable, by almost every word processing
application ever made: Microsoft Word, WordPerfect, WordPad, OpenOffice,
FreeOffice, LibreOffice, etc. This is not limited to desktop office
application either, however, as RTF is also supported by online solutions
such as Google Docs, Zoho Docs, etc.

With all that in mind, it definitely seems like it should be on the
"mandatory data types" list.

Are there any legal roadblocks to making a proprietary data format a
mandatory type? Are there any other reasons why people think that RTF
should be excluded from the list?

Please let me know and/or discuss.  Thanks!

[1] http://en.wikipedia.org/wiki/Rich_Text_Format
[2] http://www.w3.org/TR/clipboard-apis/#mandatory-data-types-1
[3] RTF spec v1.8
http://www.microsoft.com/en-us/download/details.aspx?id=7105
[4] RTF spec v1.9.1
http://www.microsoft.com/en-us/download/details.aspx?id=10725


Sincerely,
    James Greene