title: How is chrono::steady_clock's rep and period types determined?
body: <p><a href="http://en.cppreference.com/w/cpp/chrono/steady_clock" rel="nofollow noreferrer"><code>chrono::steady_clock</code></a> consists of 4 member types: <code>rep</code>, <code>period</code>, <code>duration</code>, and <code>timepoint</code>.</p>
  
  <p><code>chrono::steady_clock::duration</code> is a <code>chrono::duration&lt;rep,period&gt;</code>.
  <code>chrono::steady_clock::period</code> is a <code>ratio</code>.</p>
  
  <p>How are the types of <code>chrono::steady_clock::duration</code> and <code>chrono::steady_clock::period</code> determined?</p>
  
  <p>For example,</p>
  
  <p><code>chrono::steady_clock::duration</code> could be <code>chrono::duration&lt;int,period&gt;</code> where period is <code>ratio&lt;1,1000&gt;</code></p>
  
  <p>or</p>
  
  <p><code>chrono::steady_clock::duration</code> could be <code>chrono::duration&lt;double,period&gt;</code> where period is <code>ratio&lt;1,1000000&gt;</code>.</p>