gistfile1.txt

[clever@amd-nixos:/nix/store/i75qkyhlvjy5li19rf65jcg8hxnvzbv0-xkeyboard-config-2.22/share/X11/xkb/symbols]$ cat eurosign 
// Most keyboards have the EuroSign engraved on the E key
partial
xkb_symbols "e" {
    key <AD03>  { [  NoSymbol,   NoSymbol,   EuroSign,  NoSymbol ]      };
};
 
// Many Apple keyboards have the EuroSign engraved on the 2 key
partial
xkb_symbols "2" {
    key <AE02>  { [  NoSymbol,   NoSymbol,   EuroSign,  NoSymbol ]      };
};
 
// Some keyboards have the EuroSign engraved on the 4 key
partial
xkb_symbols "4" {
    key <AE04>  { [  NoSymbol,   NoSymbol,   EuroSign,  NoSymbol ]      };
};
 
// Many keyboards have the EuroSign engraved on the 5 key
partial
xkb_symbols "5" {
    key <AE05>  { [  NoSymbol,   NoSymbol,   EuroSign,  NoSymbol ]      };
};

gistfile2.txt

default  hidden partial modifier_keys
xkb_symbols "capslock" {
    replace key <CAPS> { [ Caps_Lock ] };
    modifier_map Lock { Caps_Lock };
};

hidden partial modifier_keys
xkb_symbols "shiftlock" {
    replace key <CAPS> { [ Shift_Lock ] };
    modifier_map Shift { Shift_Lock };
};

hidden partial modifier_keys
xkb_symbols "grouplock" {
    replace key <CAPS> { [ ISO_Next_Group, Caps_Lock ] };
};

hidden partial modifier_keys
xkb_symbols "groupshift" {
    key <CAPS> {
        type[Group1] = "PC_ALT_LEVEL2",
        [ Mode_switch, Caps_Lock ]
    };
};

hidden partial modifier_keys
xkb_symbols "swapescape" {
    key <CAPS> { [ Escape ] };
    key <ESC>  { [ Caps_Lock ] };
};

....