qmk_firmware/layouts/default/split_3x5_3/info.json

{
    "keyboard_name": "3x5+3 split layout",
    "url": "",
    "maintainer": "qmk",
    "width": 12,
    "height": 4.75,
    "layouts": {
        "LAYOUT_split_3x5_3": {
            "layout": [
                {"x":0, "y":0.25},
                {"x":1, "y":0.125},
                {"x":2, "y":0},
                {"x":3, "y":0.125},
                {"x":4, "y":0.25},

                {"x":7, "y":0.25},
                {"x":8, "y":0.125},
                {"x":9, "y":0},
                {"x":10, "y":0.125},
                {"x":11, "y":0.25},

                {"x":0, "y":1.25},
                {"x":1, "y":1.125},
                {"x":2, "y":1},
                {"x":3, "y":1.125},
                {"x":4, "y":1.25},

                {"x":7, "y":1.25},
                {"x":8, "y":1.125},
                {"x":9, "y":1},
                {"x":10, "y":1.125},
                {"x":11, "y":1.25},

                {"x":0, "y":2.25},
                {"x":1, "y":2.125},
                {"x":2, "y":2},
                {"x":3, "y":2.125},
                {"x":4, "y":2.25},

                {"x":7, "y":2.25},
                {"x":8, "y":2.125},
                {"x":9, "y":2},
                {"x":10, "y":2.125},
                {"x":11, "y":2.25},

                {"x":2.5, "y":3.25},
                {"x":3.5, "y":3.5},
                {"x":4.5, "y":3.75},

                {"x":6.5, "y":3.75},
                {"x":7.5, "y":3.5},
                {"x":8.5, "y":3.25}
            ]
        }
    }
}