You may be wondering what the weird '/' is for in the binding. We couldn't just use {Binding} here and specify no Path (the default property in a binding markup extension) as the binding wouldn't 'fallback' as we described above, it would just bind to the collection. No good, we want the current item.

Fortunately, there is this forward slash syntax which effectively takes the form <collection>/<current-item-property>.

[http://www.thejoyofcode.com/Binding_to_the_Current_Item_in_WPF.aspx]