xkb remap Ctrl+j to be Ctrl+Page_Down - xkeyboard

Question

I already have an .xkb layout file with some stuff going on, basically altgr-intl with HJKL as arrow keys:
xkb_keymap {
xkb_keycodes { include "evdev+aliases(qwerty)" };
xkb_types { include "complete" };
xkb_compat { include "complete" };
xkb_symbols {
include "pc+us(altgr-intl)+inet(evdev)+altwin(swap_lalt_lwin)+capslock(swapescape)"
key <AC06> { [h, H, Left] };
key <AC07> { [j, J, Down] };
key <AC08> { [k, K, Up] };
key <AC09> { [l, L, Right] };
};
xkb_geometry { include "pc(pc104)" };
};
I want to remap Ctrl+j to Ctrl+Page_Down (and k/PgUp), but not modify any other Ctrl+* combinations.
I want to have Ctrl+Page_Down easily accessible for navigating tabs in browsers and editors.

Answer 1

This works, keeping altgr-intl intact but extending the HJKL keys, and adding some kind of Control layer:
xkb_keymap {
xkb_keycodes { include "evdev+aliases(qwerty)" };
xkb_types {
include "complete"
type "FOUR_LEVEL" {
modifiers= Shift+LevelThree+Control;
map[Shift]= Level2;
map[LevelThree]= Level3;
map[Control]= Level4;
level_name[Level1]= "Base";
level_name[Level2]= "Shift";
level_name[Level3]= "Alt Base";
level_name[Level4]= "Control";
};
};
xkb_compat { include "complete" };
xkb_symbols {
// altgr-intl is *the* best US+Spanish layout, we got really lucky here - no dead keys.
// Swap lalt with lwin, to control xmonad with the key next to spacebar *but* without activating Alt menus on apps all the time.
// Swap capslock with escape not only for vim, but for any application that uses esc to close something.
include "pc+us(altgr-intl)+inet(evdev)+altwin(swap_lalt_lwin)+capslock(swapescape)"
// HJKL vim keys in the AltGr layer, and special Ctrl-J/K remappings for the usual tab navigation.
key <AC06> { [h, H, Left ] };
key <AC09> { [l, L, Right, Left ] };
// Special Control Level4 for tab navigation
key.type = "FOUR_LEVEL";
key <AC07> { [j, J, Down, Page_Down] };
key <AC08> { [k, K, Up, Page_Up ] };
};
xkb_geometry { include "pc(pc104)" };
};