How to know if the uninstallation is invoked RemoveExistingProduct?

[Streamlet]

As the title.

If I use major upgrade, the installer willl remove the old product during an upgrade. In these case I want the user data to be kept.
When user uninstall the product manually, I want the user data to be deleted.

How can the uninstaller differentiate wher it is invoked by RemoveExistingProduct action, or by the end user?

I tried to pass a public property to the installer, but it does not pass it to the uninstaller of old version when execute RemoveExistingProduct action.

Thanks in advance.

[Streamlet]

This issue is solved. The property UPGRADINGPRODUCTCODE can tell the difference between uninstallation and major upgrade.