OpenGrok

// these variants assign various XKB keycodes to ISO_Level3_Shift so that
// the third shift level can be reached
//

// Ensure a mapping to a real modifier for LevelThree
partial modifier_keys
xkb_symbols "modifier_mapping" {
  key.type[Group1] = "ONE_LEVEL";

  replace key <LVL3> {
    symbols[Group1] = [ ISO_Level3_Shift ]
  };
  modifier_map Mod5 { <LVL3> };
};

// the default behavior is for the right Alt key (AltGr) to generate the
// third engraved symbol
default partial modifier_keys
xkb_symbols "ralt_switch" {
  key <RALT> {
    type[Group1]="ONE_LEVEL",
    symbols[Group1] = [ ISO_Level3_Shift ]
    };
  include "level3(modifier_mapping)"
};

// Right Alt key never chooses 3rd level.
// This option attempts to undo the effect of a layout's
// including ralt_switch.  You may also want to select another
// level3 option that maps the level3 shift to some other key.
partial modifier_keys
xkb_symbols "ralt_alt" {
  key <RALT> {
    type[Group1]="TWO_LEVEL",
    type[Group2]="TWO_LEVEL",
    type[Group3]="TWO_LEVEL",
    type[Group4]="TWO_LEVEL",
    symbols[Group1] = [ Alt_R, Meta_R ],
    symbols[Group2] = [ Alt_R, Meta_R ],
    symbols[Group3] = [ Alt_R, Meta_R ],
    symbols[Group4] = [ Alt_R, Meta_R ]
    };
  modifier_map Mod1    { <RALT> };
};

partial modifier_keys
xkb_symbols "ralt_switch_multikey" {
  key <RALT> {
    type[Group1]="TWO_LEVEL",
    symbols[Group1] = [ ISO_Level3_Shift, Multi_key ]
    };
  include "level3(modifier_mapping)"
};

// special case or right Alt switch - for use with grp:alts_toggle
//
partial hidden modifier_keys
xkb_symbols "ralt_switch_for_alts_toggle" {
 virtual_modifiers LAlt, AlGr;
  key <LALT> {
    type[Group1]="PC_RALT_LEVEL2",
    symbols[Group1] = [ Alt_L,  ISO_Prev_Group,  ISO_Prev_Group ],
    virtualMods= LAlt
  };
  key <RALT> {
    type[Group1]="PC_ALT_LEVEL2",
    symbols[Group1] = [ ISO_Level3_Shift, ISO_Next_Group ],
    virtualMods= AltGr
  };
  include "level3(modifier_mapping)"
};

// using the level(alt_switch) map, either Alt key temporarily chooses
// the third shift level.  (Mostly be used to imitate Mac OS functionality.)
partial modifier_keys
xkb_symbols "alt_switch" {
  include "level3(lalt_switch)"
  include "level3(ralt_switch)"
};

partial modifier_keys
xkb_symbols "lalt_switch" {
  key <LALT> {
    type[Group1]="ONE_LEVEL",
    symbols[Group1] = [ ISO_Level3_Shift ]
    };
  include "level3(modifier_mapping)"
};

// using the level(switch) map, the right Control key temporarily
// chooses the third shift level (until it is released).
partial modifier_keys
xkb_symbols "switch" {
  key <RCTL> {
    type[Group1]="ONE_LEVEL",
    symbols[Group1] = [ ISO_Level3_Shift ]
    };
  include "level3(modifier_mapping)"
};

// using the level(menu_switch) map, the Menu key temporarily
// chooses the third shift level (until it is released).
partial modifier_keys
xkb_symbols "menu_switch" {
  key <MENU> {
    type[Group1]="ONE_LEVEL",
    symbols[Group1] = [ ISO_Level3_Shift ]
    };
  include "level3(modifier_mapping)"
};

// using the level3(win_switch) map, the either Windows' logo key
// temporarily chooses the third shift level.
partial modifier_keys
xkb_symbols "win_switch" {
  include "level3(lwin_switch)"
  include "level3(rwin_switch)"
};

// using the level3(lwin_switch) map, the left Windows' logo key
// temporarily chooses the third shift level.
partial modifier_keys
xkb_symbols "lwin_switch" {
  key <LWIN> {
    type[Group1]="ONE_LEVEL",
    symbols[Group1] = [ ISO_Level3_Shift ]
    };
  include "level3(modifier_mapping)"
};

// using the level(rwin_switch) map, the right Windows' logo key
// temporarily chooses the third shift level.  If you use this map,
// you should define your keyboard as pc101 or pc102 instead of pc104
// or pc105.
partial modifier_keys
xkb_symbols "rwin_switch" {
  key <RWIN> {
    type[Group1]="ONE_LEVEL",
    symbols[Group1] = [ ISO_Level3_Shift ]
    };
  include "level3(modifier_mapping)"
};

// using the level3(enter_switch) map, the Enter key on the keypad
// temporarily chooses the third shift level.  This is especially
// useful for Mac laptops which miss the right Alt key.
partial modifier_keys
xkb_symbols "enter_switch" {
  key <KPEN> {
    type[Group1]="ONE_LEVEL",
    symbols[Group1] = [ ISO_Level3_Shift ]
    };
  include "level3(modifier_mapping)"
};

partial modifier_keys
xkb_symbols "caps_switch" {
  key <CAPS> {
    type[Group1]="ONE_LEVEL",
    symbols[Group1] = [ ISO_Level3_Shift ]
  };
  include "level3(modifier_mapping)"
};

partial modifier_keys
xkb_symbols "bksl_switch" {
  key <BKSL> {
    type[Group1]="ONE_LEVEL",
    symbols[Group1] = [ ISO_Level3_Shift ]
  };
  include "level3(modifier_mapping)"
};

partial modifier_keys
xkb_symbols "lsgt_switch" {
  key <LSGT> {
    type[Group1]="ONE_LEVEL",
    symbols[Group1] = [ ISO_Level3_Shift ]
  };
  include "level3(modifier_mapping)"
};

partial modifier_keys
xkb_symbols "caps_switch_latch" {
  key <CAPS> {
    type[Group1]="THREE_LEVEL",
    symbols[Group1] = [ ISO_Level3_Shift, ISO_Level3_Shift, ISO_Level3_Latch ]
  };
  include "level3(modifier_mapping)"
};

partial modifier_keys
xkb_symbols "bksl_switch_latch" {
  key <BKSL> {
    type[Group1]="THREE_LEVEL",
    symbols[Group1] = [ ISO_Level3_Shift, ISO_Level3_Shift, ISO_Level3_Latch ]
  };
  include "level3(modifier_mapping)"
};

partial modifier_keys
xkb_symbols "lsgt_switch_latch" {
  key <LSGT> {
    type[Group1]="THREE_LEVEL",
    symbols[Group1] = [ ISO_Level3_Shift, ISO_Level3_Shift, ISO_Level3_Latch ]
  };
  include "level3(modifier_mapping)"
};