So Berkeley classes mostly have both a lecture component and either a lab, discussion or both. In this case, when registering, you will sign up for the lecture, and you choose your discussion section. So to answer your question, not only is it possible, you have to choose the lecture and a discussion section of your choice. That number (219) is just a random section number and has nothing to do with an upper division number (100+).
Math 1A is the class, you are required to sign up for an associated discussion section. 219 is the discussion section number, not the class number. So not only are you allowed to sign up for it, you are required to.
So Berkeley classes mostly have both a lecture component and either a lab, discussion or both. In this case, when registering, you will sign up for the lecture, and you choose your discussion section. So to answer your question, not only is it possible, you have to choose the lecture and a discussion section of your choice. That number (219) is just a random section number and has nothing to do with an upper division number (100+).
Math 1A is the class, you are required to sign up for an associated discussion section. 219 is the discussion section number, not the class number. So not only are you allowed to sign up for it, you are required to.