This game (PT24-S4-G4) isn't in our games set but I seemed to have difficulty applying our placeholder "system" (such as it is) .
The rule : G cannot be prescribed if both N and U are prescribed. I created the following placeholder in the out/not selected portion of my diagram: ~G/~U. As I understand it, this is a viable pick for a placeholder given this rule.
However, the global directive question (#18) has for the correct answer a configuration that includes both G and U as selected for the group.
What's up, Dave?