Decodes a file which was previously encoded with the ENCODE
    utility or encoded using a MIME aware mail agent.

1  –  Restrictions

    None.

    Syntax

      PMDF DECODE  encoded-file-spec output-file-spec

    Qualifiers            Defaults

    /ENCODING=type        None
    /FILENAME             /NOFILENAME
    /HEADER               /NOHEADER

2  –  Prompts

    Input file:   encoded-file-spec
    Output file:  output-file-spec

3  –  Parameters

 encoded-file-spec

    Specifies the name of an encoded input file. The input file must
    be a file previously created with the ENCODE utility.

 output-file-spec

    The name of the file to produce as output. The file output by
    DECODE will have the identical format, structure, contents, etc.
    of the original file encoded with ENCODE.

    When the /FILENAME qualifier is used, the output-file-spec is
    treated as a default file specification and as much as possible
    of the file name, if any, specified in the Content-type: header
    line is used to generate the actual output file name.

4  –  Description

    PMDF DECODE and ENCODE have been, for the most part, made
    obsolete by PMDF MAIL. If you use PMDF MAIL, then files which
    you send with the SEND command will be encoded automatically,
    if necessary. Encoded messages which you receive will be decoded
    automatically, if necessary, and can simply be extracted to a
    file with the EXTRACT command. If, however, you do not use PMDF
    MAIL, then read on.

    The ENCODE and DECODE utilities are provided with PMDF as a means
    of transmitting OpenVMS binary files via VMS MAIL and other non-
    MIME aware agents. With ENCODE, a file can be encoded in a format
    which uses short records containing only printable characters.
    Such files can then be transmitted through most any mail system
    without being altered (e.g., lines wrapped, characters removed
    or replaced, etc.). ENCODE preserves all file contents and all
    file attributes when encoding a file. The contents and attributes
    are properly restored when decoded with DECODE. Absolutely any
    type of OpenVMS file can be transmitted with these two utilities
    - even indexed files with multiple keys and files with extended
    semantics.

    Encoded files have two parts. The first part is a conventional
    RFC 822 message header. Header lines are used to describe the
    file format; this information includes a conventional OpenVMS
    FDL (file description language) description of the file and
    a description of the encoding used to convert the file into a
    printable form for transfer. ENCODE creates this header; DECODE
    reads it and uses the information it contains to reconstruct the
    file.

                                   NOTE

       Many encoded messages received with PMDF are automatically
       decoded for you, thus obviating the need to use PMDF DECODE
       at all. This is especially true when you use PMDF MAIL whose
       EXTRACT command will extract any MIME encoded message or
       message body part. If you use VMS MAIL, however, you can
       occasionally receive an encoded message which PMDF could not
       deliver in its decoded form to VMS MAIL owing to limitations
       of VMS MAIL itself.

5  –  Qualifiers

5.1    /ENCODING

       /ENCODING=type

    This qualifier controls the type of decoding used to decode the
    input file. The possible values for this qualifier are BASE64,
    CBASE64 (gzip compressed BASE64), BASE85, BINHEX (encoding only,
    not the file format), BTOA, HEXADECIMAL, PATHWORKS, QUOTED_
    PRINTABLE, UUENCODE, CUUENCODE (gzip compressed UUENCODE). If the
    /HEADER qualifier is specified, then it should not be necessary
    to specify the encoding used as this should be given in the
    message header. The /ENCODING qualifier will override the header
    specification if it is used.

5.2    /FILENAME

       /FILENAME
       /NOFILENAME (default)

    When the /FILENAME qualifier is used, the output-file-spec is
    treated as a default file specification and as much as possible
    of the file name, if any, specified in the Content-type: header
    line is used to generate the actual output file name. The default
    is /NOFILENAME in which case any file name specified in the
    Content-type: header line is ignored.

5.3    /HEADER

       /HEADER
       /NOHEADER (default)

    This qualifier controls whether or not the encoded file begins
    with a MIME-compliant header. /NOHEADER is the default. When
    /NOHEADER is used, the /ENCODING qualifier is usually needed
    to specify the encoding since it cannot be determined from the
    header. To decode material that begins with a MIME-compliant
    header, e.g., specifying the encoding used, use the /HEADER
    qualifier.

6  –  Examples

      The following example illustrates a typical scenario:
      SUE@SAMPLE.COM wants to send an executable program to
      BOB@EXAMPLE.COM. To do this, Sue might issue the following
      two commands:

 $ PMDF ENCODE/ENCODING=BASE64 PROGRAM.EXE PROGRAM.TXT
 $ MAIL/SUBJECT="Bob, here's the program" PROGRAM.TXT
 "IN%""BOB@EXAMPLE.COM"""

      When Bob receives this mail message he should issue the
      following commands:

 $ MAIL
 MAIL> EXTRACT/NOHEADER PROGRAM.TXT
 MAIL> EXIT
 $ ! Remove any extra material at the beginning and ending of the file.
 $ PMDF DECODE/ENCODING=BASE64 PROGRAM.TXT PROGRAM.EXE

      After decoding the file, Bob can now proceed to run
      PROGRAM.EXE.

      Note that Sue could also have used PMDF MAIL's SEND command to
      bypass the need to use PMDF ENCODE in the first place.