Setup Factory for Windows Installer
A list of condition levels for the current feature. Click the Add button to open the Condition Level Properties dialog and create a new condition level for the feature. Condition levels allow you to override the default level of a feature.
These conditions are evaluated when the CostFinalize action is executed.
MSDN Online: Condition Table
MSDN Online: Feature Table
WiX Help File: Condition Element
WiX Help File: Feature Element