{
  "er": "code units",
  "er_boundary": "code units",
  "er_source": "code units",
  "fx": "code units",
  "fx_boundary": "code units",
  "fx_source": "code units",
  "fy": "code units",
  "fy_boundary": "code units",
  "fy_source": "code units",
  "fz": "code units",
  "fz_boundary": "code units",
  "fz_source": "code units",
  "t": "code time",
  "volume": "code volume"
}