The SPCBKEY field, ulIntKey, specifies which SPCB to change. In a multitasking environment, more than one application can be running and using the Sync/Stream Manager. To prevent one application from changing an SPCB in a stream handler that another application might be using, a unique ulIntKey must be used. For example, the stream handle or the device ID can be used as the ulIntKey to provide a unique value. This also enables any given application to define more than one SPCB for the same data type. There is no way to replace an SPCB that exists in a stream handler, but because adding and deleting are supported, the same function exists. An application cannot use this function to install or remove an SPCB with ulIntKey equal to 0.
Note: The ulIntKey field of SPCBKEY must match the ulIntKey field of spcbkey in the SPCB structure.