Enter the directory value, which can be a property, environment variable, file path, or component directory path.

This is what happens at run time when you use each of the following:

Directory Value | Description
--- | ---
[PROPERTYNAME] | At run time, this resolves to the value of the specified property. It is strongly recommended that you use public properties.
[$ComponentName] | At run time, this resolves to the installation location of the specified component.
[%EnvironmentVariable] | At run time, this resolves to the value of the specified environment variable.

See Custom Action Type 35 (Target column) in the Windows Installer Help Library for more information.