title: What does the tilde (~) mean in my composer.json file?
body: <p>I have this line in my composer.json file:</p>
  
  <pre><code>"require": {
      ...
      "friendsofsymfony/user-bundle": "~2.0@dev",
      ...
  },
  </code></pre>
  
  <p>What does the tilde <code>~</code> in  <code>~2.0@dev</code> exactly mean? Is that a placeholder and shall always fetch the subversions like <code>1.2.0</code>, <code>2.2.0</code>, <code>3.2.0</code> and so on? Doesn't make sense (and would be done by the <code>*</code> wildcard).</p>
  
  <p>The <a href="http://getcomposer.org/doc/04-schema.md">composer.json documentation</a> doesn't tell anything about the tilde.</p>
  
  <p>I am asking because I just read about a <a href="http://symfony.com/blog/category/security-advisories">security issue in the Symfony blog</a> and they recommend to upgrade to version 1.3.3. But figuring out the FOSUserBundle's version isn't that easy (I couldn't find a file that contains the version).</p>