Databinding to Foreign Keys in WPF

For my current project, I have several combo boxes where the drop down list is populated by a fact table and the bound value comes from a foreign key into that table from the current object being edited.  This seems to me to be a pretty common thing to do, but damn if I could find any examples – I assumed the foreign key should be bound to the ‘SelectedValue’ property, and there is an ItemSource that I can bind to my fact table so the drop down is populated.

At this point my dropdown worked, but nothing would appear in the combobox.  I finally noticed a ‘SelectedItemPath’ property – I assumed this would be the name of the field in my dropdown that was associated to my foreign key. Sure enough, that’s exactly what it is.

Pretty easy solution, but I was just amazed that there is no documentation on these properties – MSDN and Google came up with nothing on ‘SelectedItemPath’