Section Header
    + name := EVENT_KEYBOARD;
    - comment :="Keyboard event.";
Section Inherit
    + parent_event:Expanded EVENT;
Section Public
    - source:INBOX :=
    + key:UINTEGER_16;
    + prev:EVENT_KEYBOARD;
    - set_prev new_prev:EVENT_KEYBOARD <-
    - make c:UINTEGER_16 <-
Display.
    - display <-
    - copy_from evt:EVENT_KEYBOARD <-