Printing FAQ's:

4/0: full-colour front (4) and blank on the back (0), commonly used for the printed card at the back of the packaged cd (the traycard).

4/1: full-colour (4) front and monocolor black on the back (1). Commonly used for CD single-fold front inserts, in which the inside of the booklet contains black & white liner notes and credits, and the front and back (which when unfolded are actually on the same side) are in full-colour.

4/4: full-colour both sides. The most expensive way to print!

Film: Final output of your digital artwork in colour separations which are used on a traditional offset printing press.

Insert: folded or stapled front cover of a compact disc.

Traycard: The "back cover" of a compact disc, which fits under the plastic tray which holds the cd. Unless one is using a clear plastic tray, your traycard is only printed on one side (the side visible when the cd is flipped over).