MoSCoW is a method that is used in business and particularly in software development to get an understanding with the customer on the importance they place on the delivery of each functional requirement. It originated as part of the Dynamic Systems Development Method. Sometimes called a MoSCoW list or a MOSCOW Analysis. MoSCoW stands for:

• M - MUST have this.
• S - SHOULD have this if at all possible.
• C - COULD have this if it does not affect anything else.
• W - WON'T have this time but WOULD like in the future.

The o's in MoSCoW are added to make the word pronounceable, and are often left lower case to indicate that they don't stand for anything.

via WikiPedia.org

Something rather obvious but you have to admire the way it is captured. Plus you can guess that I didn't go in search of this one specifically