Hi Scott Isaacson, Thursday (18 September 1997)
Per our IPP telecon yesterday, the new IETF MIME extension for parameter
value language tags (RFC 2184, August 1997, N. Freed and K. Moore), is
excerpted below.
An asterisk ("*") is used at the END of a parameter 'name', to indicate
that character set and/or language tags are present, at the BEGINNING
of the parameter 'value', each delimited by a right single quote ("'").
Cheers,
- Ira McDonald (outside consultant at Xerox)
High North Inc
PO Box 221
Grand Marais, MI 49839
906-494-2434
----------------------------- From RFC 2184 ----------------------------
Network Working Group N. Freed
Request for Comments: 2184 Innosoft
Updates: 2045, 2047, 2183 K. Moore
Category: Standards Track University of Tennessee
August 1997
MIME Parameter Value and Encoded Word Extensions:
Character Sets, Languages, and Continuations
[...]
1. Abstract
This memo defines extensions to the RFC 2045 media type and RFC 2183
disposition parameter value mechanisms to provide
(1) a means to specify parameter values in character sets
other than US-ASCII,
(2) to specify the language to be used should the value be
displayed, and
(3) a continuation mechanism for long parameter values to
avoid problems with header line wrapping.
This memo also defines an extension to the encoded words defined in
RFC 2047 to allow the specification of the language to be used for
display as well as the character set.
[...]
4. Parameter Value Character Set and Language Information
Some parameter values may need to be qualified with character set or
language information. It is clear that a distinguished parameter
name is needed to identify when this information is present along
with a specific syntax for the information in the value itself. In
addition, a lightweight encoding mechanism is needed to accomodate 8
bit information in parameter values.
Asterisks ("*") are reused to provide the indicator that language and
character set information is present and encoding is being used. A
single quote ("'") is used to delimit the character set and language
information at the beginning of the parameter value. Percent signs
("%") are used as the encoding flag, which agrees with RFC 2047.
Specifically, an asterisk at the end of a parameter name acts as an
indicator that character set and language information may appear at
the beginning of the parameter value. A single quote is used to
separate the character set, language, and actual value information in
the parameter value string, and an percent sign is used to flag
octets encoded in hexadecimal. For example:
Content-Type: application/x-stuff;
title*=us-ascii'en-us'This%20is%20%2A%2A%2Afun%2A%2A%2A
Note that it is perfectly permissible to leave either the character
set or language field blank. Note also that the single quote
delimiters MUST be present even when one of the field values is
omitted. This is done when either character set, language, or both
are not relevant to the parameter value at hand. This MUST NOT be
done in order to indicate a default character set or language --
parameter field definitions MUST NOT assign a default character set
or lanugage.
----------------------------- From RFC 2184 ----------------------------