-switch enables a transformation to decode each base64 and
-quoted-printable text message part to the selected 8bit or 7bit
-encoding. If 7bit is selected for a base64 part but it will only fit
-8bit, as defined by RFC 2045, then it will be decoded to 8bit
-quoted-printable. Otherwise, if the decoded text would not fit the
-selected encoding, the part is not decoded (and a message will be
-displayed if
+switch enables a transformation to decode each base64 and quoted-printable
+text message part to the selected 8-bit, 7-bit, or
+binary encoding.
+If 7-bit is selected for a base64 part but it will only fit
+8-bit, as defined by RFC 2045, then it will be decoded to 8-bit
+quoted-printable.
+Similarly, with 8-bit, if the decoded text would be binary,
+then the part is not decoded (and a message will be displayed if