Complex sentence: Floppy disks formatted using XDF cannot be read in floppy disk drives that are not attached directly to the system by way of a FDC; for example, USB attached floppy drives cannot read XDF formatted media.
Split into simpler sentences: Floppy disks formatted using XDF can only be read in floppy disk drives that are attached directly to the system by way of a FDC. Thus, USB attached floppy drives cannot read XDF formatted media.