doc link: https://doc.qt.io/QtInterfaceFramework/idl-syntax.html#type
The page says "External types are from an external module, and they need to be referenced with their fully qualified name, module.<name>." 
In the following snippet, I assume the type Station is imported from the common module, but it's not written as common.Station, which seems to be contradicting to what the sentence above it says.