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.
- The Wolfram Language 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]]]]].
Introduced in 1991