How to use Money Flow Index?

Stock XOMA.

What does MFI tell you?

Thanks

http://moneycentral.msn.com/investor/charts/chartdl.aspx?PT=3&compsyms=&D4=1&DD=1&D5=2&DCS=2&MA0=0&MA1=0&CF=32&D8=1&D7=&D6=&showchartbt=Redraw+chart&symbol=XOMA&nocookie=1&SZ=0