BB1 serial Setup

I am trying to cable up and is confused with the serial cabling. I have 2 WIC-1T  and NM-8A/S

When I look at bb1,txt, I see it runs from serial 0- 9 ( serial 7 and 8 has no ip)

On which wic do I start serial 0?

also there is a line in bb1.txt for  interface BV1 (Any idea what is this for?)

I am new and want to learn the correct way. Any help would be appreciated

Thanks