请教USB驱动程序中的一条指令的含义？

谁能解释一下驱动程序自定义例程中这句话的意思：
if(I.IoctlOutputBufferSize()||I.IoctlInputBufferSize()||I.IoctlBuffer())和
if(!I.IoctlBuffer()||(I.IoctlInputBufferSize()!=sizeof(DWORD))||I.IoctlOutputBufferSize())        
 谢谢啦！！

这是一个例子：
__try
  {
// TODO: Verify that the input parameters are correct
//If not, return STATUS_INVALID_PARAMETER
if(I.IoctlOutputBufferSize()||I.IoctlInputBufferSize()
||I.IoctlBuffer())                              
__leave;
// TODO: Handle the the USBD12_IOCTL_START_AD request, or
//defer the processing of the IRP (i.e. by queuing) and set
//status to STATUS_PENDING.
PURB pUrb = m_Lower.BuildVendorRequest(
NULL,
0,
0,
D12×××,
0
);
status = m_Lower.SubmitUrb(pUrb,NULL,NULL,5000L);
  }
  __finally
  {

// TODO: Assuming that the request was handled here. Set I.Information
// to indicate how much data to copy back to the user.
I.Information() = 0;
I.Status()=status;

  }
  return status;
}
为啥I.IoctlOutputBufferSize()、I.IoctlInputBufferSize()
和I.IoctlBuffer()都不为1时才发送urb？
向各位大侠请教啦？先谢谢啦