Optional Output Parameters in the Profiling API
In the profiling API, all output parameters (specified by [out] in the method syntax) are optional, unless a method has only one output parameter. A profiler passes null for any output parameters it is not interested in. The profiler must also pass consistent values for any input parameters that are associated with the output parameter. For example, if a null output parameter represents a buffer to be filled with data, the input parameter that specifies the buffer's size must be set to 0.