[This is preliminary documentation and subject to change.]
The BlockInstall action displays an error dialog and then blocks the current installation if the FindRelatedProducts action finds a newer version of the product on the system.
This action queries the Operator and Property columns of the Upgrade table. The value of the operator specifies whether to block the installation of the pending upgrade of the product.
The BlockInstall action terminates the installation if the properties set by the FindRelatedProducts action are set when the action executes.
The BlockInstall action only stops the installation if the properties are still set when the action is executed. For example, a dialog may be authored that warns the user that a newer version of the application has been found. If the user chooses to perform the current install anyway, the dialog may unset the appropriate property to allow the installation to proceed.