:group 'eword-decode
   :type '(repeat symbol))
 
+(defun eword-decode-field-body
+  (field-name field-body &optional unfolded max-column)
+  "Decode header field body FIELD-BODY, and return the result.
+
+If FILED-BODY is already unfolded, UNFOLDED should be non-nil.
+
+If MAX-COLUMN is non-nil, result is folded with MAX-COLUMN.
+(Or `fill-column' if MAX-COLUMN is t.)
+Otherwise, the result is unfolded.
+
+If FIELD-NAME is in `eword-decode-ignored-field-list',
+return FIELD-BODY itself.
+
+If FIELD-NAME is in `eword-decode-structured-field-list',
+FIELD-BODY is interpreted as structured field,
+decode MIME encoded-words and return it.
+
+Otherwise, FIELD-BODY is interpreted as unstructured field,
+decode MIME encoded-words and return it.
+
+Anyway, non-encoded-word part is decoded with `default-mime-charset'."
+  (when (symbolp field-name)
+    (setq field-name (symbol-name field-name)))
+  (when (eq max-column t)
+    (setq max-column fill-column))
+  (let ((field-name-symbol (intern (capitalize field-name)))
+       (len (string-width field-name)))
+    (if (memq field-name-symbol eword-decode-ignored-field-list)
+       ;; Don't decode
+       (if max-column
+           field-body
+         (std11-unfold-string field-body))
+      (if (memq field-name-symbol eword-decode-structured-field-list)
+         ;; Decode as structured field
+         (if max-column
+             (eword-decode-and-fold-structured-field
+              field-body len max-column t)
+           (eword-decode-and-unfold-structured-field field-body))
+       ;; Decode as unstructured field
+       (if max-column
+           (eword-decode-unstructured-field-body field-body len)
+         (eword-decode-unstructured-field-body
+          (std11-unfold-string field-body) len))))))
+
 (defun eword-decode-header (&optional code-conversion separator)
   "Decode MIME encoded-words in header fields.
 If CODE-CONVERSION is nil, it decodes only encoded-words.  If it is