This is xnu-8019. See this file in:
Directory listing for xnu-8019//iokit/IOKitUser
IOBlockStorageDevice.h
IOBufferMemoryDescriptor.h
IODataQueueDispatchSource.h
IODispatchQueue.h
IODispatchSource.h
IOInterruptDispatchSource.h
IOMemoryDescriptor.h
IOMemoryMap.h
IOService.h
IOTimerDispatchSource.h
IOUserServer.h
Makefile
OSAction.h
OSArray.h
OSBoolean.h
OSCollection.h
OSContainer.h
OSData.h
OSDictionary.h
OSNumber.h
OSObject.h
OSSerialization.h
OSString.h