[Unix] dd is a command on Unix and Unix-like operating systems whose primary purpose is to convert and copy a file. On Unix, device drivers for hardware (such as hard disks) and special device files (such as /dev/zero and /dev/random) appear in the file system just like normal files; dd can also read and/or write from/to these files, provid... Found on http://en.wikipedia.org/wiki/Dd_(Unix)
Direct Drive. A method of controlling one form of auto iris lens (the other is video iris), where the electronic has been removed from the lens and is built into the camera. To use a DD lens with a camera, the camera must have a DD output.
Found on http://www.zoo.co.uk/~z0001325/Glossary.html