Using One Context Node's Info in the Setter of Another

I am very new to WebUI.

I have a view. In its context, it already uses context node BUILHeader . I need to create a field based on BP_NUMBER info in BUILHeader and place the derived information on the screen.

I created a new context node that has a field DerivedValue in it. I think I am supposed to populate it in it's P_Setter. How do I make he information from BUILHeader available to my setter.

I think this is simple, but I'm new. so I need a good code example here.

Thank you .

...Mike