{
  "chapters": [
    {
      "id": "overview",
      "title": "Overview",
      "summary": "What the ApsisRS kernels cover and how the layers are organized.",
      "documents": ["overview", "architecture-apsis-rs", "standards-and-provenance"]
    },
    {
      "id": "time",
      "title": "Time",
      "summary": "Time scales, leap seconds, and calendar conversions.",
      "documents": ["time-scales", "leap-seconds", "calendar-and-mjd"]
    },
    {
      "id": "geometry",
      "title": "Frames and geodesy",
      "summary": "Reference frames, the Earth Rotation Angle, and the WGS 84 ellipsoid.",
      "documents": ["reference-frames", "earth-rotation-angle", "geodesy-wgs84"]
    },
    {
      "id": "elements",
      "title": "Element sets",
      "summary": "The two-line element format and the Keplerian elements.",
      "documents": ["tle-format", "keplerian-elements"]
    },
    {
      "id": "propagation",
      "title": "Propagation",
      "summary": "Analytical and numerical orbit propagation, and how they compare.",
      "documents": ["sgp4", "perturbations", "propagator-comparison", "ephemeris-interpolation"]
    }
  ]
}