Installation and Upgrade > Upgrade Reference > Windchill Upgrade Manager > Glossary
  
Glossary
Review the following terms to gain a better understanding as you read the upgrade documentation.
Source System
The Windchill release that your production system is currently running. It is the older Windchill release.
Target System
The new Windchill release. It is the system to which you will be upgrading.
Windchill Solution
A Windchill solution includes all of the products, optional products, third party products and components that comprise the installed PTC software for your enterprise. The PTC Solution Installer (PSI) allows you to select what to install as part of your Windchill solution.