Correct file name extension for MIME 'text/enriched' file format?

Question

Emacs offers the ability to use the MIME standard text/enriched for writing enriched text. What is the canonical file name extension for this format. Emacs seems to think it's .doc (see $EMACSDIR/24.1/etc/enriched.doc), but this could be confused with the more common Microsoft Word .doc format. Is there an alternative?

(I know it's not .rtf, which is a format different from both Microsoft's .doc and MIME's text/enriched formats)

EDIT:

It seems that .etf and .txte are some accepted extensions for this file type.

Answer 1

Due to its intended use as an inline mail format, I don't think there is a standard file extension for it. .txte seems to be another extension that is used for it though, which does not clash with other well-known formats.

Answer 2

text/enriched is also known as Enriched Text Format or .etf.

http://users.starpower.net/ksimler/eudora/etf.html

http://filext.com/file-extension/ETF