Data model dotted line mean what ?

Hi All

I just notice that there are dotted line in data model , what does it mean ? it is mean not healthy ? Because i notice that my Target table also have Date field link to master calendar , and sales table also have date field link to master calendar , so i think the dotted line mean i dont need to link the target table date field dont need to link to sales table again . it is correct ? that why dotted line came out.