title: what is 1..n, ?..m and these symbols in ERD?
body: <p>I'm new to ERD, I know 1:1 means one to one. 
  1:n one to many. 
  m:1 many to one. 
  m:n many to many</p>
  
  <p>but what are these symbols mean is ERD?<br>
  image from "software idea modeler v11.55": <a href="http://s8.picofile.com/file/8326381876/Capture.JPG" rel="nofollow noreferrer">http://s8.picofile.com/file/8326381876/Capture.JPG</a>
  <a href="https://i.stack.imgur.com/jIz1e.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/jIz1e.jpg" alt="here are symbols"></a></p>