Webgl game asset format.One asset consists of: 1-N materials, 1-N meshes (defining removable model parts), 0-1 skeletons (optional), 0-K animations (optional). The asset is loaded from two separate files: a JSON file (see below) and a binary buffer (Uint8Array) containing all data.

WebGLAssetFormat

{
    "materials": [
        {
            "diffuse":  "model_D.jpg",
            "specular": "model_S.jpg",
            "normal":   "model_N.jpg"
        }
    ],
    "meshes": {
        "body": {
            "vertex_count":      100,
            "triangle_count":    60,
            "material_index":     0,
            "indices": {"type": "uint32", "byte_offset": 0, "stride": 3, "count": 60},
            "position": {"type": "float", "byte_offset": 200, "stride": 3, "count": 100},
            "normal": {"type": "float", "byte_offset": 400, "stride": 3, "count": 100},
            "texcoord": {"type": "float", "byte_offset": 600, "stride": 2, "count": 100},
            "boneweight": {"type": "float", "byte_offset": 800, "stride": 4, "count": 100},
            "boneindex": {"type": "uint8", "byte_offset": 1200, "stride": 4, "count": 100},
        }
    },
    "bones": [
        {
            "name": "root",
            "parent": -1,
            "skinned": false,
            "invBindMat": [1,0,0,0, 0,1,0,0, 0,0,1,0, 0,0,0,1],
            "pos": [0,0,0],
            "rot": [0,0,0,1],
            "scl": [1,1,1]
        }
    ],
    "animations": [
        {
            "name": "run_forward",
            "fps": 30,
            "frames": 20,
            "tracks": [
                {
                    "pos": {"type": "float", "byte_offset": 1400, "stride": 3, "count": 300},
                    "rot": {"type": "float", "byte_offset": 1600, "stride": 4, "count": 300},
                    "scl": {"type": "float", "byte_offset": 1800, "stride": 3, "count": 300},
                }
            ]
        }
    ]
}

are you aware of gltf? seems similar with a quick look.

at least it has the similar structure of json + binary etc.