Very often you wish to send the same letter to many different people; hence, the text of each letter is the same but the salutations will be different. There are two ways to go about generating such a series of letters. The only difference between them is that the first is somewhat more conservative of computer time, but it can only be used for relatively short letters; the second is a bit more demanding of computer time, but it doen't care how long the letter is. By a short letter I mean one which is no more than one or two pages in length.