MIME gzip64 en/decoding(not yet specified in RFC).
-z
The same as -g.
-u
Uudecoding.
-l length
Line
length
into which base64/quoted-printable/gzip64 encoding truncate.
-t
On base64/gzip64 encoding, local newline is treated as CRLF.
On base/gzip64 decoding, any newline is translated
into local newline.
Specify this option only when the input is a line
based object(e.g. Content-Type: is text/plain or
application/postscript).