I have a project involving an interface DLL that was developed using two files, sde80.lib and pe80.lib in Visual Studio 2005 with C++. The information I have indicates this was developed using the ArcSDE 8.0 SDK C API. The system this DLL works with has moved on to the latest versions of GIS and SDE, and now the DLL is having trouble communicating with the Geodatabase using the provided functions from these two files. I've been trying with little success to find an equivalent SDK for the current versions so I can upgrade the DLL. I've read about an ArcSDE 10 C API that matches the functionality I have but I have not been able to find out where I can acquire it. Would anyone be able to direct me to where I might find it, or what software package would contain it? If I can find this information out I can work with the client to obtain it. Thanks.