RFC 2046, "Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types", November 1996Source of RFC: 822ext (app)
Errata ID: 6800
Publication Format(s) : TEXT
Reported By: Daniel Shahaf
Date Reported: 2021-12-27
Section 5.1.4 says:
In the case where one of the alternatives is itself of type "multipart" and contains unrecognized sub-parts, the user agent may choose either to show that alternative, an earlier alternative, or both.
It should say:
In the case where one of the alternatives is itself of type "multipart" and contains unrecognized sub-parts, the user agent may choose to either show that alternative, show an earlier alternative, or let the user choose which alternative to show.
The quoted sentence conflicts with the following sentence later in the same section:
What is most critical, however, is that the user not
automatically be shown multiple versions of the same data. Either
the user should be shown the last recognized version or should be
given the choice.
I assume the correction should be as proposed, but other options are conceivable.