Globally unique identifiers are 16-byte data structures that you can use to identify objects in a globally unique way. Whenever a GUID is required in an API, a symbol representing that GUID should be used. The symbols are either defined in one of the DirectPlay header files or the application developer must generate them. You can generate GUIDs by using the Guidgen.exe utility that comes with Microsoft Visual C++. For example, every application must define an application GUID that identifies the application that is running in a session.
Note If there are different versions of an application that cannot interoperate in the same session, they should have different application GUIDs to distinguish them.
To use DirectPlay-defined GUIDs successfully in your application, you must either define the INITGUID symbol prior to all other include and define statements, or you must link to the Dxguid.lib library. If you define INITGUID, you should define it in only one of your source modules.