How many times have you written a brief and you're on page 10 and you want to refer to something above that's on page 5. So, you write “See page 5, supra.” But later you put some new material before page 5, and page 5 becomes page 7. Now your reference is no longer accurate. Then, unless you forget, you manually change 5 to 7. However, that can be tedious if you have four or five or more cross-references. And, even if you only have one, you might forget to make the change.
That’s the problem. For the solution—instructions on updating cross-references automatically—read the rest of A.J.’s post.