Any encoded-words so recognized are decoded, and if possible, the resulting unencoded text is displayed in the original character set.
When displaying a particular header field that contains multiple encoded-words, any linear-white-space that separates a pair of adjacent encoded-words is ignored. (This is to allow the use of multiple encoded-words to represent long strings of unencoded text, without having to separate encoded-words where spaces occur in the unencoded text.)
In the event other encodings are defined in the future, and the mail reader does not support the encoding used, it may either (a) display the encoded-word as ordinary text, or (b) substitute an appropriate message indicating that the text could not be decoded.
If the mail reader does not support the character set used, it may (a) display the encoded-word as ordinary text (i.e., as it appears in the header), (b) make a "best effort" to display using such characters as are available, or (c) substitute an appropriate message indicating that the decoded text could not be displayed.
If the character set being used employs code-switching techniques, display of the encoded text implicitly begins in "ASCII mode". In addition, the mail reader must ensure that the output device is once again in "ASCII mode" after the encoded-word is displayed.