Remove features during upgrade

[woreid]

I'm new to installation software. I have a question. How do I know which features are being removed during an uninstall? From what I understand, if I specify REMOVE=<feature1>,<feature2> on the Install MSI command, it passes those to the setup. I want to be able to check for those so I know whether I need to remove any prereqs or simply just remove the specified features. (i.e. if REMOVE=ALL, I would remove the prereqs too).