What is the 8 day / 70 hour on duty limit?

The 8 day / 70 hour limit:
If your company does operate vehicles every day of the week, your employer may assign you to the 70-hour/8-day schedule. This means that you are not allowed to drive after you've been on duty 70 hours in any 8 consecutive days. Once you reach the 70 hour limit, you will not be able to drive again until you have dropped below 70 hours for an 8 consecutive day period. You may do other work, but you cannot do any more driving until you get below the limit. Any other hours you work, whether they are for a motor carrier or someone else, must be added to the total.