What is meant by the terms margin and turnover in ROI calculations?

Margin and turnover in ROI calculations:

Margin: In ROI calculation margin is the ratio of net operating income to total sales.

Turnover: In ROI calculation turnover means the ratio of total sales to average operating assets.

Operating assets include cash, A/R, inventory, PP&E, and so on. Land held for future use, leases, and investments do not count.