The InstallCondition attribute on the package elements that participate in a Bundle Chain (namely: ExePackage, MsiPackage, MspPackage, MsuPackage) indicates whether the package should be installed or not. If the condition evaluates to true, then the package may be installed. If the condition evaluates to false, then the package should not be installed. If the package is present and the condition evaluates to false the package will be uninstalled.

As always, the BootstrapperApplication can override the default decision made by the engine by modifying the requested state in the PlanPackageBegin callback.