title: What are the [(special function)] in wordpress, and how do I enable them for my plugin?
body: <p>I'm wanting to include a function into a WordPress page, but since WordPress doesn't allow the use of <code>&lt;?php ?&gt;</code> tags I cannot add the functions regularly.</p>
  
  <p>I noticed when using a gallery plugin that it added <code>[flagallery gid=1 name="Gallery"]</code> to the page content (when editing the page in visual mode). Is there some way to set this up in my plugin?</p>
  
  <p>Like on my page have <code>[myPlugin category=myCategory]</code> run:</p>
  
  <pre><code>function myPlugin($category) {
      echo ...
  }
  </code></pre>