is a global variable which, if set, is applied to the symbol name and tag of messages that are requested but have not yet been defined.
- $NewMessage is applied to the symbol name, tag, and language of a message if an explicit language is specified.
- Mathematica looks for the value of or after $NewMessage has been applied.
- You can set up $NewMessage to read the text of messages from files when they are first needed.
- A typical value for $NewMessage might be Function[ToExpression[FindList[files, ToString[MessageName[#1, #2]]]]].
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