Lock Application when Idle

Afternoon,

Just hoping to get some clarification on an option under Security for RDM, Lock Application when Idle - does idle mean when the machine itself is idle for a period of time or when the application is open and left idle but the machine still being worked on? For example if we have RDM open but then the users works on an Excel spreadsheet outside of RDM, would RDM lock if this option is set to lock when idle after 15mins?

Thanks as always
Rich