Various causes: There are very many causes, from congestive heart failure, to lymphedema, to venous insufficiency, blood clots, pregnancy, a various other causes, including serious and not-so-serious causes.
I have a Sony DVP ns55p blu-ray player with a usb port in the front. The player requires that the usb flash device (thumb drive) be formatted in FAT32in order to recognize it.
More recently the term combo drive is used to refer to an optical drive that can read & write CDs and DVDs, but only read Blu-ray Disc/BD-ROM; some manufacturers refer this as Blu-Ray Disc combo drive or BD-ROM/DVDÂ±RW/CD-RW drive.