title: How can I determine that Windows Installer is performing an upgrade rather than a first time install?
body: <p>I have an install that upgrades a previous version of an app if it exits. I'd like to skip certain actions when the install is upgrade mode. How can I determine if the install is running in upgrade mode vs. first time install mode?</p>
  
  <p>I'm using Wise Installer, but I don't think that matters. I'm assuming that Windows Installer has a property that is set when the installer is in upgrade mode. I just can't seem to find it. If the property exists, I'm assuming I could use it in a conditional statement.</p>