We call this the GET INFO key. When you are in a field which has a list of possible answers, pressing the F6 key will display this list. You move your cursor to the item you want, press Enter, and your choice will be pasted into the entry field.
There is also the F9 or Calculate key. This allows you to enter any APL expression which will be evaluated and inserted in the current entry field. Note that F6: GET INFO will give a list of previously used expressions, starting from the most recently used.
Due to some conflicts with most Windows environment, we have set up an alternate Print Screen key as Ctrl+F6. Note that this is a bit more intelligent than the standard Print Screen key: where you are viewing or editing a list or table that is larger than the screen, it prints the entire list or table, and not just the part you can see on the screen.
There is also the F5 or Pop Up key. Pressing this key gets
you a pop up menu, usually with Application specific options. The default
menu for ATS is:
Usually you are in a field which requires a number. In most cases entering a 0 will solve your problem. Where you have also just added a line to a list of information, and you do not want to keep it, simply press Alt+F4