Сочетание клавиш - @as []. Что это означает?

Что означает это сочетание клавиш? Есть ли список определений для символов привязки ярлыков?

velociraptor@JurassicPark:~$ gsettings get  org.gnome.desktop.wm.keybindings maximize-horizontally
@as []

Редактировать: Я составил список всех своих горячих клавиш, и на основании этого я считаю разумным предположить, что @as [] означает, что ключ не установлен. Я прав?

activate-window-menu        ['<Alt>space']
begin-move                  ['<Alt>F7']
begin-resize                ['<Alt>F8']
close                       ['<Alt>F4']
cycle-group                 ['<Alt>F6']
cycle-group-backward        @as []
cycle-panels                ['<Control><Alt>Escape']
cycle-panels-backward       @as []
cycle-windows               ['<Alt>Escape']
cycle-windows-backward      @as []
lower                       @as []
maximize                    @as []
maximize-horizontally       @as []
maximize-vertically         @as []
minimize                    ['<Primary><Alt>KP_0']
move-to-center              @as []
move-to-corner-ne           ['<Primary><Alt>KP_Prior']
move-to-corner-nw           ['<Primary><Alt>KP_Home']
move-to-corner-se           ['<Primary><Alt>KP_Next']
move-to-corner-sw           ['<Primary><Alt>KP_End']
move-to-side-e              ['<Primary><Alt>KP_Right']
move-to-side-n              ['<Primary><Alt>KP_Up']
move-to-side-s              ['<Primary><Alt>KP_Down']
move-to-side-w              ['<Primary><Alt>KP_Left']
move-to-workspace-1         ['<Super><Shift>1', '<Super><Alt>1']
move-to-workspace-10        @as []
move-to-workspace-11        @as []
move-to-workspace-12        @as []
move-to-workspace-2         ['<Super><Shift>2', '<Super><Alt>2']
move-to-workspace-3         ['<Super><Shift>3', '<Super><Alt>3']
move-to-workspace-4         ['<Super><Shift>4', '<Super><Alt>4']
move-to-workspace-5         ['<Super><Shift>5', '<Super><Alt>5']
move-to-workspace-6         ['<Super><Shift>6', '<Super><Alt>6']
move-to-workspace-7         ['<Super><Shift>7', '<Super><Alt>7']
move-to-workspace-8         ['<Super><Shift>8', '<Super><Alt>8']
move-to-workspace-9         ['<Super><Shift>9', '<Super><Alt>9']
move-to-workspace-down      ['<Control><Shift><Alt>Down']
move-to-workspace-left      ['<Super><Shift>Left', '<Super><Alt>Left']
move-to-workspace-right     ['<Super><Shift>Right', '<Super><Alt>Right']
move-to-workspace-up        ['<Control><Shift><Alt>Up']
panel-main-menu             ['<Super>space', '<Alt>F2']
panel-run-dialog            @as []
raise                       @as []
raise-or-lower              @as []
set-spew-mark               @as []
show-desktop                ['<Super>Down', '<Super>s']
switch-group                ['<Alt>Above_Tab']
switch-group-backward       @as []
switch-panels               ['<Control><Alt>Tab']
switch-panels-backward      @as []
switch-to-workspace-1       ['<Super>1']
switch-to-workspace-10      @as []
switch-to-workspace-11      @as []
switch-to-workspace-12      @as []
switch-to-workspace-2       ['<Super>2']
switch-to-workspace-3       ['<Super>3']
switch-to-workspace-4       ['<Super>4']
switch-to-workspace-5       ['<Super>5']
switch-to-workspace-6       ['<Super>6']
switch-to-workspace-7       ['<Super>7']
switch-to-workspace-8       ['<Super>8']
switch-to-workspace-9       ['<Super>9']
switch-to-workspace-down    ['<Control><Alt>Down']
switch-to-workspace-left    ['<Super>Left']
switch-to-workspace-right   ['<Super>Right']
switch-to-workspace-up      ['<Control><Alt>Up']
switch-windows              ['<Alt>Tab']
switch-windows-backward     ['<Alt><Shift>Tab']
toggle-above                @as []
toggle-fullscreen           @as []
toggle-maximized            ['<Super>Up', '<Primary><Super>Up', '<Primary><Alt>KP_5']
toggle-on-all-workspaces    @as []
toggle-shaded               ['<Primary><Alt>s']
unmaximize                  ['<Alt>F5']