+ default-keymap-or-function
+ representation-type)
+ "View RAW-BUFFER in MIME-View mode.
+Optional argument PREVIEW-BUFFER is either nil or a name of preview
+buffer.
+Optional argument DEFAULT-KEYMAP-OR-FUNCTION is nil, keymap or
+function. If it is a keymap, keymap of MIME-View mode will be added
+to it. If it is a function, it will be bound as default binding of
+keymap of MIME-View mode.
+Optional argument REPRESENTATION-TYPE is representation-type of
+message. It must be nil, `binary' or `cooked'. If it is nil,
+`binary' is used as default."