If you want to use an encoding that isn't listed in this paragraph, you should do as it says and go look in the IANA encodings list. Mind you, that list is far from easy to use.
It would seem that most commercial products are likely to be able to handle ASCII, ISO-8859-1, and a couple of JIS dialects, along with the UTF encodings. So it would be a very good idea to stick with one of these.
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