<p>The key to these is the terminology in the course name displayed by schedule.berkeley.edu</p>
<p>For example, PHYSICS 8B P 001 LEC is physics 8b, P is the primary session for the class, it is lecture 001 and there is another lecture as an alternative, PHYSICS 8B P 002 LEC</p>
<p>Then most classes have discussion sessions in addition to the lecture. These are secondary, thus PHYSICS 8B S 101 DIS and PHYSICS 8B S 201 DIS where the S means secondary to the main lecture, DIS means discussion and 101 or 201 is the number of that discussion. When you see the first digit of all the discussions matching the lecture number, it lets you know that you have to pick a discussion aligned with the same lecture - if you choose lecture 002, then you would have to pick one of the 2xx discussions. </p>
<p>Some classes also have laboratory work. PHYSICS 8B S 201 LAB is a secondary class, type is laboratory, and because the first digit starts with 2, it is aligned with lecture 2. For most classes with both lab and discussion, you pick the same number for both - discussion 201 and lab 201. </p>
<p>If there is only one lecture choice, any discussion will do. </p>
<p>Sometimes the discussion or lab is NOT tied to a particular lecture. CHEMISTRY 1A P 001 LEC, CHEMISTRY 1A P 002 LEC, and CHEMISTRY 1A P 003 LEC are three choices for lecture, but the lab sections are independent. You pick any lab you want and any lecture. CHEMISTRY 1A S 110 LAB is one lab choice, but so are CHEMISTRY 1A S 230 LAB, CHEMISTRY 1A S 330 LAB whcih so far look like labs aligned with lectures 1 2 and 3 but then you see CHEMISTRY 1A S 420 LAB, CHEMISTRY 1A S 520 LAB, CHEMISTRY 1A S 640 LAB, CHEMISTRY 1A S 700 LAB and even CHEMISTRY 1A S 850 LAB, but there are only three lecture sections! The instructions in the writeup of lecture tell you to pick any lab and any lecture. They are not aligned. Also, this particular class has no discussion sessions (that function is done by the GSI in part of the lab time). Interestingly, while you sign up for a specific lecture, in this particular class you have the flexibility to sit in the other lecture if that is more convenient in a particular week or day, as they stay strictly synchronized.</p>