I know content with @type != text/* or */xml *+xml MUST be Base64 encoded, but what about content with those magic types ... should the spec say that they MUST NOT be Base64 encoded? How would I send plain text which contains control codes (eg <FF>, <BELL>, etc) in a <content> element? Am I forced to put them in a separate file and refer via @src? Even if they are very short pieces of text? e.