title: VTiger beginner - where are these items?
body: <p>I am a beginner to Vtiger and I want to get a modification done. I need to understand the order of Vtiger functions.</p>
  <p>So here are my questions:</p>
  <ol>
  <li><p>What folder contains the bulk of the PHP functions? (Ex. vlib?), I searched all of the module files, these seem to call function included from somewhere else.</p>
  <p>To better define why I need to understand these locations, here is what I want to do: I need to modify the line items of a Product or Service in a Quote by adding a field. (I have already added the field to my MySQL table).</p>
  </li>
  <li><p>Where is the folder that contains the &quot;update&quot; function for Products and Services?<br />
  Next I need the new information to appear on the quote output to PDF.</p>
  </li>
  <li><p>Where is the folder that contains the quote query function?</p>
  </li>
  </ol>
  <p>I seek answers that might help anyone who reads this speed up their learning curve of the Vtiger architecture, I do not expect anyone to do the work for me.</p>