title: Modifying one of OpenERP's core fields using a custom module
body: <p>Sometimes our OpenERP users want to make a small change to a field in a core OpenERP module. For example, they want the product screen's Rack, Row, and Case fields to be longer than 16 characters.</p>
  
  <p>Can I change an existing field without making changes to the module that declared it? I'd rather make the changes using our own custom module, instead of editing the <code>product</code> module itself.</p>