encoding

    Required parameter specifying the file encoding to use. The
    available encodings are: 8BIT, 7BIT, BASE32, BASE64, CBASE64
    (gzip compressed BASE64), BASE85, BINHEX (encoding only, not
    the BINHEX file format), BTOA, HEXADECIMAL, PATHWORKS, QUOTED_
    PRINTABLE, UUENCODE, and CUUENCODE (gzip compressed UUENCODE).