PMDF System Manager's Guide
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6.2 Character Set Conversion

If PMDF probes and finds that the message is to be reformatted, it will proceed to check each part of the message. Any text parts are found and their character set parameters are used to generate the second probe. Only when PMDF has checked and found that conversions may be needed does it ever perform the second probe. The input string in this second case looks like this: 


IN-CHAN=in-channel;OUT-CHAN=out-channel;IN-CHARSET=in-char-set
The in-channel and out-channel are the same as before, and the in-char-set is the name of the character set associated with the particular part in question. If no match occurs for this second probe, no character set conversion is performed (although message reformatting, e.g., changes to MIME structure, may be performed in accordance with the keyword matched on the first probe). If a match does occur it should produce a string of the form: 


OUT-CHARSET=out-char-set
Here the out-char-set specifies the name of the character set to which the in-char-set should be converted. Note that both of these character sets must be defined in the character set definition table, charsets.txt , located in the PMDF table directory. No conversion will be done if the character sets are not properly defined in this file. This is not usually a problem since this file defines several hundred character sets; most of the character sets in use today are defined in this file. See the description of the PMDF CHBUILD (OpenVMS) or pmdf chbuild (UNIX and NT) utility in Chapter 29 and Chapter 30 for further information on the charsets.txt file.

If all the conditions are met, PMDF will proceed to build the character set mapping and do the conversion. The converted message part will be relabelled with the name of the character set to which it was converted.

6.2.1 Converting DEC-MCS to ISO-8859-1 and Back

Suppose that DEC-MCS is used locally, but this needs to be converted to ISO-8859-1 for use on the Internet. In particular, suppose the connection to the Internet is via a set of TCP channels (including but not limited to tcp_local ), and l and d channels are in use locally. The table shown in Example 6-1 brings such conversions about.

Example 6-1 Converting DEC-MCS to and from ISO-8859-1 

CHARSET-CONVERSION 
 
  IN-CHAN=l;OUT-CHAN=tcp_*;CONVERT                 Yes 
  IN-CHAN=d;OUT-CHAN=tcp_*;CONVERT                 Yes 
  IN-CHAN=tcp_*;OUT-CHAN=l;CONVERT                 Yes 
  IN-CHAN=tcp_*;OUT-CHAN=d;CONVERT                 Yes 
  IN-CHAN=*;OUT-CHAN=*;CONVERT                     No 
  IN-CHAN=l;OUT-CHAN=tcp_*;IN-CHARSET=DEC-MCS      OUT-CHARSET=ISO-8859-1 
  IN-CHAN=d;OUT-CHAN=tcp_*;IN-CHARSET=DEC-MCS      OUT-CHARSET=ISO-8859-1 
  IN-CHAN=tcp_*;OUT-CHAN=l;IN-CHARSET=ISO-8859-1   OUT-CHARSET=DEC-MCS 
  IN-CHAN=tcp_*;OUT-CHAN=d;IN-CHARSET=ISO-8859-1   OUT-CHARSET=DEC-MCS

6.2.2 Converting DEC-KANJI to ISO-2022-JP and Back

The table shown in Example 6-2 specifies a conversion between local usage of DEC Kanji and the ISO 2022 based JP code used on the Internet.

Example 6-2 Converting DEC-Kanji to and from ISO-2022-JP 

CHARSET-CONVERSION 
 
  IN-CHAN=l;OUT-CHAN=l;CONVERT                      No 
  IN-CHAN=l;OUT-CHAN=d;CONVERT                      No 
  IN-CHAN=d;OUT-CHAN=l;CONVERT                      No 
  IN-CHAN=d;OUT-CHAN=d;CONVERT                      No 
  IN-CHAN=l;OUT-CHAN=*;CONVERT                      Yes 
  IN-CHAN=d;OUT-CHAN=*;CONVERT                      Yes 
  IN-CHAN=*;OUT-CHAN=l;CONVERT                      Yes 
  IN-CHAN=*;OUT-CHAN=d;CONVERT                      Yes 
  IN-CHAN=l;OUT-CHAN=*;IN-CHARSET=DEC-KANJI         OUT-CHARSET=ISO-2022-JP 
  IN-CHAN=d;OUT-CHAN=*;IN-CHARSET=DEC-KANJI         OUT-CHARSET=ISO-2022-JP 
  IN-CHAN=*;OUT-CHAN=l;IN-CHARSET=ISO-2022-JP       OUT-CHARSET=DEC-KANJI 
  IN-CHAN=*;OUT-CHAN=d;IN-CHARSET=ISO-2022-JP       OUT-CHARSET=DEC-KANJI

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