(prop("Parent") ? prop("Parent").at(0).prop("Outline") + "." + prop("Order") : prop("Order")) .upper()
Explained
/* Check if Parent has a value */ (prop("Parent") /* If it does, display the parent's Outline value */ ? prop("Parent").at(0).prop("Outline") /* Then output a period followed by the value of Order */ + "." + prop("Order") /* Otherwise, display the value of Order */ : prop("Order")) /* Capitalise the result */ .upper()