@@ -17,7 +17,7 @@ def __init__(self, _data, _subtype='octet-stream',
                  _encoder=encoders.encode_base64, *, policy=None, **_params):
         """Create an application/* type MIME document.
 
-        _data is a string containing the raw application data.
+        _data contains the bytes for the raw application data.
 
         _subtype is the MIME content type subtype, defaulting to
         'octet-stream'.
 
@@ -18,7 +18,7 @@ def __init__(self, _audiodata, _subtype=None,
                  _encoder=encoders.encode_base64, *, policy=None, **_params):
         """Create an audio/* type MIME document.
 
-        _audiodata is a string containing the raw audio data.  If this data
+        _audiodata contains the bytes for the raw audio data.  If this data
         can be decoded as au, wav, aiff, or aifc, then the
         subtype will be automatically included in the Content-Type header.
         Otherwise, you can specify  the specific audio subtype via the
 
@@ -17,7 +17,7 @@ def __init__(self, _imagedata, _subtype=None,
                  _encoder=encoders.encode_base64, *, policy=None, **_params):
         """Create an image/* type MIME document.
 
-        _imagedata is a string containing the raw image data.  If the data
+        _imagedata contains the bytes for the raw image data.  If the data
         type can be detected (jpeg, png, gif, tiff, rgb, pbm, pgm, ppm,
         rast, xbm, bmp, webp, and exr attempted), then the subtype will be
         automatically included in the Content-Type header. Otherwise, you can