Calls the AbortIO vector of the appropriate device to stop an asynchronously started io request before completion. This may or may not be done. You still have to do a WaitIO() on the iorequest structure.
INPUTS
iORequest
Pointer to iorequest structure.
RESULT
Errorcode if the abort request failed, 0 if the abort request went well. io_Error will then be set to IOERR_ABORTED.