As previously stated, this line is used for entering text to be interpreted by the editor as commands. If you have just entered the editor you should have a cursor on the left margin of your command line. There will also be an inactive cursor (rectangular block) in the text area. Whenever you type a character (excluding cursor and most function keys) it will appear where the active cursor is, and the cursor will move to the right.
Now try to enter a few commands to change your options. Most options are enabled by typing
o{option_character}+
and disabled by typing
o{option_character}-
or, they can be toggled by typing
o{option_character}~
First let's turn on option blank by typing the string ob+ followed by a carriage return. You can turn it off by typing ob- followed by a carriage return. Finally, you can toggle it by typing ob~ followed by a carriage return. A toggle causes the option to change state. If it was previously off it will be turned on and if it was previously on it will be turned off.
Should you make a typing error you may delete characters by pressing the Backspace key or may delete the entire line by pressing the Ctrl and X key simultaneously. Both of these keys work on the line containing the active cursor and are similar to the line editing keys of the command interpreter for the QNX2 operating system which this editor originated in. (The line editing in the QNX 4 shell is considerably different.)
If you type in an unknown command or do something which causes an error, an error message will be displayed on the command line and held until you type a carriage return to clear it. Try typing in "abc" followed by a carriage return to generate an error, then clear it by typing another carriage return.
You may execute any system command from the editor command line by preceding it with an exclamation mark (!). For example, to invoke the ls utility to display the contents of the current working directory:
!ls
or to invoke another qed editor to edit another file:
!qed another_file
The second example will invoke another copy of the editor. When you leave you will return to this editing session.