# MIME::Decoder::NBit - phpMan

## NAME
    [MIME::Decoder::NBit] - encode/decode a "7bit" or "8bit" stream

## SYNOPSIS
    A generic decoder object; see [MIME::Decoder] for usage.

## DESCRIPTION
    This is a [MIME::Decoder] subclass for the "7bit" and "8bit" content
    transfer encodings. These are not "encodings" per se: rather, they are
    simply assertions of the content of the message. From RFC-2045 Section
    6.2.:

       Three transformations are currently defined: identity, the "quoted-
       printable" encoding, and the "base64" encoding.  The domains are
       "binary", "8bit" and "7bit".

       The Content-Transfer-Encoding values "7bit", "8bit", and "binary" all
       mean that the identity (i.e. NO) encoding transformation has been
       performed.  As such, they serve simply as indicators of the domain of
       the body data, and provide useful information about the sort of
       encoding that might be needed for transmission in a given transport
       system.

    In keeping with this: as of MIME-tools 4.x, *this class does no
    modification of its input when encoding;* all it does is attempt to
    *detect violations* of the 7bit/8bit assertion, and issue a warning (one
    per message) if any are found.

  Legal 7bit data
    RFC-2045 Section 2.7 defines legal "7bit" data:

       "7bit data" refers to data that is all represented as relatively
       short lines with 998 octets or less between CRLF line separation
       sequences [RFC-821].  No octets with decimal values greater than 127
       are allowed and neither are NULs (octets with decimal value 0).  CR
       (decimal value 13) and LF (decimal value 10) octets only occur as
       part of CRLF line separation sequences.

  Legal 8bit data
    RFC-2045 Section 2.8 defines legal "8bit" data:

       "8bit data" refers to data that is all represented as relatively
       short lines with 998 octets or less between CRLF line separation
       sequences [RFC-821]), but octets with decimal values greater than 127
       may be used.  As with "7bit data" CR and LF octets only occur as part
       of CRLF line separation sequences and no NULs are allowed.

  How decoding is done
    The decoder does a line-by-line pass-through from input to output,
    leaving the data unchanged *except* that an end-of-line sequence of CRLF
    is converted to a newline "\n". Given the line-oriented nature of 7bit
    and 8bit, this seems relatively sensible.

  How encoding is done
    The encoder does a line-by-line pass-through from input to output, and
    simply attempts to *detect* violations of the "7bit"/"8bit" domain. The
    default action is to warn once per encoding if violations are detected;
    the warnings may be silenced with the QUIET configuration of
    [MIME::Tools].

## SEE ALSO
    [MIME::Decoder]

## AUTHOR
    Eryq (<eryq@zeegee.com>), ZeeGee Software Inc (<http://www.zeegee.com>).

    All rights reserved. This program is free software; you can redistribute
    it and/or modify it under the same terms as Perl itself.