qmk_firmware/layouts/default/ortho_3x3/info.json

{
    "keyboard_name": "3x3 ortholinear layout",
    "url": "",
    "maintainer": "qmk",
    "layouts": {
        "LAYOUT_ortho_3x3": {
            "layout": [
                {"x":0, "y":0},
                {"x":1, "y":0},
                {"x":2, "y":0},

                {"x":0, "y":1},
                {"x":1, "y":1},
                {"x":2, "y":1},

                {"x":0, "y":2},
                {"x":1, "y":2},
                {"x":2, "y":2}
            ]
        }
    }
}