title: Packagist.org: what does it mean when a package has a version number like: 4.4.x-dev?
body: <p>When browsing the packagist.org repositories you see packages with these version numbers e.g. If you look at the <a href="https://packagist.org/packages/phpunit/phpunit" rel="nofollow">Phpunit repo</a></p>
  
  <p>There are a few instances </p>
  
  <ul>
  <li><code>4.5.x-dev</code></li>
  <li><code>4.3.x-dev</code></li>
  <li><code>4.2.x-dev</code></li>
  </ul>
  
  <p>Do these packages contain the current work the developers are performing towards basic updates, security and bugfixes etc on an otherwise basically stable package?</p>