This function returns the value of a Windows Installer property. It exists to allow your custom action a much greater chance of being able to be tested from the command line.
If your custom action is deferred then you probably wish to use "VbsCaCadGet" instead.
When being tested you will be prompted for a "test" value for the property.
The function takes these parameters:
<$VbsCaEntry "Install"> dim InstallDir : InstallDir = VbsCaPropertyGet("INSTALLDIR", "C:\tmp\INSTALLDIR.TST", "") <$/VbsCaEntry>