ATHENA offers a variety of data processing chores -- chores which modify the data or its parameters in some way to prepare it for more extensive analysis. With the exception of merging data groups, all data processing features are accesses through the Data menu, shown below. All the entries in the Data menu, replace the main window with a tool specially designed for the data processing chore.
You can work on more than one data group in any tool without having to return to the main menu. Clicking on a group label in the group list will make that group current, display parameters appropriate to the data processing tool, sometimes plotting the data in some appropriate manner.
When you are finished using the data processing tool, you can press the button labeled “Return to the main window”. Doing so will close the special tool and redisplay the main window.