title: Magento's module config.xml complete guide?
body: <p>It's been hard to try to find a complete guide to the config file of a module (usually placed in app/code/local/PackageName/ModuleName/etc/config.xml). I understand some basic tags like </p>
  
  <pre><code>&lt;global&gt;
      &lt;models&gt;
          &lt;customclass&gt;
              &lt;class&gt;PackageName_CustomClass_Model&lt;/class&gt;
          &lt;/customclass&gt;
      &lt;/models&gt;
  &lt;/global&gt;
  </code></pre>
  
  <p>It's declaring a model and i can get this model class by using <code>Mage::getModel('modulename/customclass')</code></p>
  
  <p>However there are many other tags that don't look familiar to me at all and it's been hard trying to figure out which does what, is there any complete guide to all those tags? Or for example can someone explain what this does?</p>
  
  <pre><code>&lt;global&gt;
      &lt;sales&gt;
          &lt;quote&gt;
              &lt;totals&gt;
                  &lt;modulename&gt;
                      &lt;class&gt;modulename/sales_quote_address_total_modulename&lt;/class&gt;
                      &lt;after&gt;subtotal&lt;/after&gt;
                      &lt;before&gt;shipping&lt;/before&gt;
                  &lt;/modulename&gt;
              &lt;/totals&gt;
          &lt;/quote&gt;
      &lt;/sales&gt;
  &lt;/global&gt;
  </code></pre>
  
  <p>And how is this being called in the php files? Thanks.</p>