title: What does the colon mean in this set-builder notation?
body: <p>The instructions say: "Let D be a relation on the natural numbers (N) defined by D = { (m,n) : m | n }"</p>
  
  <p>How does one read this set-builder notation? I don't remember seeing any colons like this in lecture.</p>
  
  <p>Any help is appreciated!</p>