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MsgBox(My.ThisAddIn.Description & vbNewLine & My.ThisAddIn.Version & vbNewLine & My.ThisAddIn.Author)
I just created an add-in in Visual Studio using the wizard.
It looks like the wizard created a class named ThisAddIn:
/// <summary>
/// A class for looking up declarative information in the associated configuration xml file (.esriaddinx).
/// </summary>
internal static class ThisAddIn {
The class is in the file Config.Designer.cs.
Is this what you were looking for?