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Practical consequences
PDF files open as usual but not all features are enabled automatically. When opening a file from a network drive or a file downloaded from the web, the program gives a message and asks the user to confirm whether additional features in the file should be enabled.
By selecting "Enable All Features" the user confirms that the features should be enabled.
When opening a file downloaded from the web, the software asks whether the source should be trusted and the additional features should be enabled.