What's the best format for a language file?
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When you create a PHP script which outputs text and you want to be able to let the user of the script set the language, what's the best format for a language file?

 1. Database
 2. CSV file
 3. XML file
 4. JSON file
 5. Anything else?

Keep in mind that the user of the script will need to be able to change some words in the language file, so the easier the better.

 