Lets you enable the Keep Window display, if the window is not empty.
OFF
Lets you disable the Keep Window display, suppressing the contents without discarding it.
Usage Notes:
If no argument is specified, the KEEP command is sensitive to the current cursor position. When the cursor is positioned on a data line within the display, that line is added to the Keep Window. When the cursor is positioned on a line within the Keep Window, that line is removed from the Keep Window.
Data cannot be added or removed from the Keep Window when the window is disabled.
