digraph int {
    node [shape = circle, width = 0.6, height = 0.6, fontname = "monospace", fixedsize = true, fontsize = 12];
    edge [fontname = "monospace", fontsize = 12];

    node [shape = circle];
        START; ZX;

    node [style = filled];
        Z D O H L U UL;
    
    node [shape = circle, fixedsize = true];
        START -> Z [ label = "0" ];
        START -> D [ label = "[1-9]" ];

        Z -> ZX [ label = "[Xx]" ];
        Z -> O [ label = "[0-7]" ];
        Z -> U [ label = "[Uu]" ];
        Z -> L [ label = "[Ll]" ];

        D -> D [ label = "[0-9]" ];
        D -> U [ label = "[Uu]" ];
        D -> L [ label = "[Ll]" ];

        ZX -> H [ label = "<hex>" ];

        O -> O [ label = "[0-7]" ];
        O -> L [ label = "[Ll]" ];
        O -> U [ label = "[Uu]" ];

        H -> H [ label = "<hex>" ];
        H -> L [ label = "[Ll]" ];
        H -> U [ label = "[Uu]" ];

        L -> UL [ label = "[Uu]" ];
        
        U -> UL [ label = "[Ll]" ];

}