pin assignment in Quartus II

In a similar vein, I am trying to understand what ends up in the Assignment Editor after a pin assignment. In my case, I'm using Quartus II 13.1 Web Edition with the DE0-Nano. In the Pin Planner, I assigned the 50MHz clock, resulting in the following:

Node Name: CLK_50

Direction: Input

Location: PIN_R8

In the Assignment Editor, this shows up as:

Status: ? 'To' name unrecognized

To: CLK_50 (with a question mark icon)

Assignment Name: Location

Value: PIN_R8

Entity: (grayed out)

However, there's another option in the Assignment Editor for "Assignment Name": external pin connection. In this case, I can enter the following:

Status: Ok

To: CLK_50

Assignment Name: External Pin Connection

Value: R8

Entity: (my top-level entity name)

So which is more correct? It certainly seems like the "External Pin Connection" would be the most accurate, but I cannot seem to find any documentation about when that should be used. And it doesn't quite seem to be associated to the Pin Planner. So now I am just confused.