I have a piece up today on ESPN.com that outlines the many steps a general manager must go through before making a trade. One of the key elements of that process is convincing the owner why that trade needs to be made.
What a GM will often do is create what's called a "trade sheet," which is basically a summary of why he wants to trade a certain player (or players), and an explanation of the players he is trying to acquire in return. Since the owner is not as well versed on the quality of players in other organizations, this is an easy way to distill the information.
Using Carlos Beltran as an example, here's what a hypothetical trade sheet might look like: