openusb_xfer_wait, openusb_xfer_aio -- Issue synchronous I/O request, Issue asynchronous I/O request openusb_ctrl_xfer, openusb_intr_xfer, openusb_bulk_xfer, openusb_isoc_xfer -- Issue synchronous Control, Interrupt, Bulk, Isochronous request openusb_abort -- Abort previous I/O requestopenusb_wait, openusb_poll -- Wait for I/O request completion, Poll completion status of I/O requestopenusb_start, openusb_stop -- Start multi-xfer mode I/O; Stop multi-xfer mode I/OFunctions in this group are used to transfer USB data. OpenUSB implements transfer APIs, including synchronous and asynchronous, defined in openusb 1.0 interface. The synchronous means when such API is used, it will block until a transfer request is accomplished or timeout. The asynchronous means such interface will returns immediately no matter success or failure. Application can use callback mechanism or other openusb 1.0 interface to check asynchronous request.