[tag=MD] [tag=VB] [tag=DT] [□]
[tag=MD] [tag=VB] [tag=DT] [□=□]
[tag=MD] [tag=VB] [tag=DT] [!□]
In our magazine project , some but not all Contents subclasses can have subtitles , so we can define a slot subTitle and simultaneously assign it to multiple classes .