Tool Palette API applications always use COM, ObjectARX, and XML. They also usually require AutoCAD extension APIs and MFC. An additional COM layer, ATL (Active Template Library), simplifies coding, but it imposes its own learning curve. Reconciling the basic infrastructure of a Microsoft-defined MFC/ATL DLL project with the unique requirements of ObjectARX applications can be confusing and time consuming. Fortunately, the ObjectARX SDK provides utilities that simplify this work.