In a double, where two constrictions are available, improved cylinder and modified are a good pairing, especially in fixed-choke guns. If screw-in chokes are an option, try a more forgiving match, like skeet and light modified. Shoot the more open barrel first on the covey rise, then the tighter barrel as the birds make their escape.
The CD and DVD have a single track of data in the form of a spiral, which starts as the center going outwards. The data is stored on the bumps or pits which are then read by the CD/DVD layer. The bumps/pits on a DVD are much smaller than on CD, allowing the DVD to store more data.
Which is the difference between Audio CD and Data CD. An Audio CD is a music CD like that you buy in a music store. It can be played on any standard CD player (such as a CD deck, or your car CD player, or a portable CD player). Music is stored on Audio CDs as uncompressed digital data, no data is lost and quality is very high, exactly as in WAV digitally encoded files. When you put an Audio CD into your personal computer CD player and play it, audio is extracted on the fly and played by your PC sound hardware.