Ok, i'm sure you're gonna think i'm an idiot, but when someone says cl id number, is it section or cl?

alright, so i'm trying to figure out when i have lunch during the school day. there are 4 possible lunch times:4a,4b,5a,5b. you look at where your homeroom time is on your schedule. if its 4th or 5th period, and then you check the cl id number (if the number is odd it's b if even it's a). my homeroom is 4th period, so i either have 4a or 4b, but i don't know which one. what would the cl id number be?? is it the same as "section id"?