Choosing Classes

<p>I was looking under in the "Look-up or Select Classes" Section under the U of I thing where you register for classes. I was wondering what is the difference between </p>

<p>the Cap(Section Capacity), Act(Section Actual), Rem(Section Remaining) AND
the XL Cap (Crosslist Capacity), XL Act (Crosslist Actual), XL Rem (Crosslist Remaing) </p>

<p>How will I know when a class that I want to take is completely filled is it when the Rem says 0 or when the XL Rem says 0</p>