The macro definitions retrieved from the context file specified
    in the Context File field of the main window are displayed in the
    Macro Definitions field of this dialog box.

    The effects of clicking on the dialog buttons are as follows:

    o  Enter - to add a new macro definition to the Macro Definitions
       list shown in the dialog box.

    o  Replace - to replace the selected macro definition in the
       Macro Definitions list.

    o  Remove - to remove the selected macro definition from the
       Macro Definitions list.

    o  OK - to dismiss the dialog box and write changes made to the
       current context.

    o  Cancel - to dismiss the dialog box, discarding current changes
       made.

    o  Help - to bring up a help window containing text describing
       the dialog box.