USE-RETURN The "Return" (or "Enter") key typically terminates entry. If you specify the USE-RETURN style, the "Return" key is instead used by the ActiveX control when it is active. For example, if the ActiveX control is a text editor or if it offers a command prompt, the USE-RETURN style would allow the user to start a new line by pressing "Return." Without this style, pressing "Return" would terminate input.
USE-TAB The "Tab" key is typically used to move between fields or controls. If you specify the USE-TAB style, "Tab" key pushes are instead used by the ActiveX control when it is active. This allows the user to enter a tab into the ActiveX control, but prevents the user from using the "Tab" key to leave the control.
USE-ALT The user can normally activate a control by typing its key letter in combination with some other special key. Under Microsoft Windows, key letters are typed in conjunction with the "Alt" key. If you specify the USE-ALT style, "Alt" key pushes are instead used by the ActiveX control when it is active. This allows the user to enter an Alt-key combination into the ActiveX control, but prevents the user from using an Alt-key combination to activate another control.