I'll tell you something about this Buz, 'cause I know you're gonna help me with my classes question
You usually start a set of working drawings with the site plan. The site plan becomes drawing 1, on sheet A1. The level 1 floor plan is drawing 2, sheet A2. You might have room for level 2 floor plan on sheet A2, so it becomes drawing 3, sheet A2. On the floor plans, you will show a section line indicating where-abouts the section is taken through...the first one will be called section a-a, and will refer the 'user' to the sheet that the section is printed on (eg A4). The drawing title for section a-a (on sheet A4) will show a-a, and A2, which indicates that the 'user' should look at sheet A2 to see where the section was cut thru.
Sing out if u want me to go on&on&on