All fields listed in the Group dialog must contain data....

# C.2.5 All fields listed in the Group dialog must contain data....

The Group dialog shows the Manufacturer, Description and part number (Title) of the new definition. Initial values are based on selected turnouts and structures or on the last Ungrouped object. The dialog also contains a toggle button (Replace with new group?), which is used if you want to replace the selected objects with the new definition. All fields listed in this dialog window must contain data.

Refer to section 2.9.3 for detail.