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This procedure is called when a string attribute is parsed by DL_expandString() to expand the tokens and environment variables the attribute may contain. DL_userGetString is passed two empty string arrays and it is expected to fill the first one with the tokens to look for and the second one with their replacement strings. The user defined token substitution is done after the built-in tokens substitution. If a user-defined token is identical to a built-in token, the user-defined one will be used.
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