IPP> RFC 2184 language tags for parameter values

IPP> RFC 2184 language tags for parameter values

IPP> RFC 2184 language tags for parameter values

Ira Mcdonald x10962 imcdonal at eso.mc.xerox.com
Thu Sep 18 11:12:09 EDT 1997


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 ----------------------------



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