Control Linear Array Depth Parametrically

[Anonymous]

I can control the spacing of the array, the thickness and even the length of the shelves in my parameters but, alas, I cannot control the depth of my shelves.

I want the formula for the depth to be =Wall_Depth-Back_Wall_Thickness but even just manually changing the length of the Shelf_Depth creates an error. 

[Alfredo_Medina]

Use a nested shelf, with its depth controlled by a parameter. Then, load that shelf into a host, and make the array.