Verifying the COM Library Version
The COM Library defines a major version number and a minor version number and provide these in a header file that is compiled with the COM application. Any application must then compare these compiled numbers with the version of the available library and if the available library is incompatible the application cannot use COM. Similarly, a .DLL should check the library version in its initialization code and fail loading if the library is incompatible or otherwise disable its COM functionality. The current major and minor version numbers are retrieved from COM Library with the function CoBuildVersion.