EPMV - Earnings Per Thousand Visitors
Depending on what you use as your base unit (pageviews or ad impressions), it is a measure of the revenue earned per page viewed or per ad viewed.
Neither metric is particularly valuable when you are talking about a website as a whole.
For example, lets assume that RPM is per page viewed. If you were to change your site so that each visitor views twice as many pages, the amount earned per page would likely drop. However, because you now get twice as many page views in total, the amount earned overall would be higher. So, in a situation like that, the RPM measurement would show a decrease in performance, even though the overall earnings are increasing, but the earnings per 1,000 visitors metrics would show the correct increase. EPMV also truly accounts for a wide range of contributory measurements: CPC/CPM/RPM/PV/V etc. which is why we find it to be the most accurate measurement of how well the website is doing overall.
When comparing relative metrics - having a good baseline (visits) is far more consistent and difficult to fudge than the baseline of RPM (revenue per thousand pageviews or ad impressions).