What is "PowerRating"?

I saw a news letter in Yahoo by TradingMarkets.com. It talked several stocks. It mentions PowerRating.(http://biz.yahoo.com/tm/070809/16165.html?.v=1)

Anyone knows what is definition of the PowerRating?

What is the average, if exists, of the power rating of the stocks?

Is it better if a stock has higher PowerRating?

Is this PowerRating useful and helpful when we determin an individual stock?

Thanks in advance!