Right, Acorn4.

Examples of possible actions taken during mastering:

Editing minor flaws
Applying noise reduction to eliminate clicks, dropouts, hum and hiss
Adjusting stereo width
Adding ambience
Equalize audio across tracks
Adjust volume
Dynamic range expansion or compression
Peak limit

To finish mastering a CD the track markers must be inserted along with ISRC, PQ codes,[further explanation needed] text and other information necessary to replicate a CD. Vinyl LP and cassettes have their own pre-duplication requirements for a finished master.

That is from Wikipedia, but it's fairly clear and accurate.

The whole article is at

http://en.wikipedia.org/wiki/Audio_mastering

The part you mention Acorn4 is in the bottom line; it's called Peak Limit.

What is seldom mentioned is the time between songs on the CD. IMO, using a flat "There will be 2 or 2.5 or 3 seconds between each song" is a mistake. Some songs may require more. It has to feel right to you, CB. After everyone else has done with your work, the name they remember is yours. You get the applause and you get the boos, not the other people who did stuff. That's also why you get the last word, and the bills. If the various people along the way do not understand what you want to hear then find others who will listen to you. Best wishes to you.