title: Role name in association relationship
body: <p>From the UML bible, about <em>role</em>:</p>
  
  <blockquote>
    <p>Role: A role name explains how an object participates in the relationship. 
    Each object needs to hold a reference to the associated object or objects. The reference is held in an attribute value within the object. When there is only one association then there is only one attribute holding a reference.</p>
  </blockquote>
  
  <ol>
  <li>What does this sentence mean?</li>
  <li>Can anyone please offer an example to explain it?</li>
  </ol>