anchor.diff:         (loop for byte across (flex:string-to-octets (make-string 1 :initial-element char)
                                                       :external-format external-format)
             do (format encapsulated-stream "=~2,'0X" byte))))
  -      
         (unless (eql #\Return char)
           (setf previous-char char))
         (unless (< 127 (char-code char))
  
positive.code:                    (previous-char previous-char)
                     (external-format external-format)
                     (encapsulated-stream encapsulated-stream)) stream
      (cond
        ;; Newline processing
        ((eql char #\Newline)
         ;; Finish quoting
         (when line-has-non-ascii
           (format encapsulated-stream "?=")
           (setf line-has-non-ascii nil))
         ;; Print CR
         (write-char #\Return encapsulated-stream)
         ;; Test for end of header
  
negative.code:           (write-sequence sequence (encapsulated-stream stream)
                            :start start
                            :end end)
            (return))))))
  