In addition to following the thread suggested by Eileen, basically the SDK allows you to utilise the methods and properties of ‘business objects’ objects and functions to create addtional functionality to that provided with the product. The WebI and full client SDKs are independant of each other. e.g. if you want the WebI front end to look completely different you can rewrite it using the WebI SDK. You can add forms, combo boxes, list boxes etc, to full client reports using the BO SDK to provide pre-processing and post processing which would be coded in VBA.