If you submitted a score of 4 or 5 on the AB Calculus Advanced Placement Exam, or a score of 3 on the BC Calculus Advanced Placement Exam, you have earned AP credit* in Math 0090. This credit will appear on your transcript, so it prevents you from registering for Math 0090 (or Math 0050 and Math 0060, which cover equivalent content).
*Note: The term "credit" is not entirely accurate, since the AP score does not count toward your total number of required credits completed at Brown. A more accurate term would be "AP notation," but since that term becomes awkward quickly, the text below uses "credit."
If you submitted a score of 4 or 5 on the BC Calculus Advanced Placement Exam, you have earned AP credit in Math 0090 AND Math 0100. The credit for Math 0100 will also appear on your transcript, so it prevents you from registering for Math 0100 (or Math 0170 or Math 0190, which cover equivalent content).
If you are an incoming student, and you think there is ANY possibility that you might decide to retake a calculus course for which the AP score(s) you submit to Brown will grant you AP credit (for example, if it has been some time since you took the exam, or if you are concerned about whether you retained enough understanding to proceed to higher courses), it is a good idea to submit a "no notation" request for your calculus AP score(s). This prevents the AP credit from being recorded on your Brown transcript, allowing you to register for the course you would have passed out of. You will receive information on how to do this during the summer before you arrive at Brown.
If you submit this request before the August deadline sent to you by e-mail, you will be allowed to add the AP credit later if necessary (for example, if you decide during shopping period that you are ready for the next calculus course after all, after attending courses at different levels). If you submit a "no notation" request late, the request may not be granted, and if it is granted, it will be permanent. So if you make your decision after the deadline, you forfeit the right to change your mind.
In general, if you are unsure of whether to continue in calculus or retake material you've already seen, we in the math department almost always recommend you try the more advanced course first. (It's a more productive choice academically, and it's easier to move down if necessary than to move up.) But initially declining your AP credit gives you more flexibility in terms of course choice, and if you do so by the August deadline, you retain the ability to have it added later.