SLAM Toolbox: Difference between Offline and Online Async/Sync launch files
I've gone through most of the material provided regarding the slam toolbox, but still not quite sure about the difference between the offline launch mode and the online async or sync modes. Already have an idea of what online synchronous mode and online asynchronous mode are and when and why we should use them from the Slam toolbox talk in the ROS developers podcast. Nevertheless, it was not mentioned about the offline mode in any of the references concerning the slam toolbox.
Any help on describing what exactly this offline launch file is and what is the main difference of it among online launch files is appreciated. Also, enlighten me if there's any document that I could follow up to know a bit more on the launch files stated in this main repo of slam toolbox.
Thanks in advance