Gets a custom extension for this SmartTag object.
This type or member is intended to be used only in projects for the 2007 Microsoft Office system. Smart tags are deprecated in Office 2010..
Assembly: Microsoft.Office.Tools.Excel (in Microsoft.Office.Tools.Excel.dll)
A custom extension is an implementation of the ISmartTagExtension interface in an Excel solution that is created by using the Office development tools in Visual Studio.