The following sections describe using the built-in installer properties and additional properties defined by the package author. Properties can be either public properties or private properties. Every property that needs to be defined upon initialization of the installer must have its name and initial value listed in the Property table. Properties having a Null value are not listed in the Property table. You can get or set properties from programs and custom actions and set public properties from the command line. The installation process can be modified by using properties in conditional statements.