File: //usr/local/share/man/man3/MIME::Decoder::NBit.3pm
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.\" ========================================================================
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.IX Title "MIME::Decoder::NBit 3"
.TH MIME::Decoder::NBit 3 "2017-04-05" "perl v5.26.3" "User Contributed Perl Documentation"
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.SH "NAME"
MIME::Decoder::NBit \- encode/decode a "7bit" or "8bit" stream
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
A generic decoder object; see MIME::Decoder for usage.
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
This is a MIME::Decoder subclass for the \f(CW\*(C`7bit\*(C'\fR and \f(CW\*(C`8bit\*(C'\fR content
transfer encodings. These are not \*(L"encodings\*(R" per se: rather, they
are simply assertions of the content of the message.
From \s-1RFC\-2045\s0 Section 6.2.:
.PP
.Vb 3
\& 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.
.Ve
.PP
In keeping with this: as of MIME-tools 4.x,
\&\fIthis class does no modification of its input when encoding;\fR
all it does is attempt to \fIdetect violations\fR of the 7bit/8bit assertion,
and issue a warning (one per message) if any are found.
.SS "Legal 7bit data"
.IX Subsection "Legal 7bit data"
\&\s-1RFC\-2045\s0 Section 2.7 defines legal \f(CW\*(C`7bit\*(C'\fR data:
.PP
.Vb 6
\& "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.
.Ve
.SS "Legal 8bit data"
.IX Subsection "Legal 8bit data"
\&\s-1RFC\-2045\s0 Section 2.8 defines legal \f(CW\*(C`8bit\*(C'\fR data:
.PP
.Vb 5
\& "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.
.Ve
.SS "How decoding is done"
.IX Subsection "How decoding is done"
The \fBdecoder\fR does a line-by-line pass-through from input to output,
leaving the data unchanged \fIexcept\fR that an end-of-line sequence of
\&\s-1CRLF\s0 is converted to a newline \*(L"\en\*(R". Given the line-oriented nature
of 7bit and 8bit, this seems relatively sensible.
.SS "How encoding is done"
.IX Subsection "How encoding is done"
The \fBencoder\fR does a line-by-line pass-through from input to output,
and simply attempts to \fIdetect\fR violations of the \f(CW\*(C`7bit\*(C'\fR/\f(CW\*(C`8bit\*(C'\fR
domain. The default action is to warn once per encoding if violations
are detected; the warnings may be silenced with the \s-1QUIET\s0 configuration
of MIME::Tools.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
MIME::Decoder
.SH "AUTHOR"
.IX Header "AUTHOR"
Eryq (\fIeryq@zeegee.com\fR), ZeeGee Software Inc (\fIhttp://www.zeegee.com\fR).
.PP
All rights reserved. This program is free software; you can redistribute
it and/or modify it under the same terms as Perl itself.