What does the number key means in log-power-timestamp.session

I get a log-power session from my iPhone analyze, I want to know the power consuming of my app, power_metrics as below:

  "power_metrics" : {
    "network_io" : {
      "cellular" : {
        "totalUpload" : 4478468,
        "totalDownload" : 223284091
      },
      "wifi" : {
        "totalUpload" : 195605789,
        "totalDownload" : 1233202961
      }
    },
    "display_apl" : {
      "totalFrameCount" : 209019,
      "averagePixelLuminance" : 38
    },
    "app_energy" : {
      "bg_audio" : {
        "10" : 563,
        "6" : 70,
        "4" : 25,
        "2" : 26,
        "7" : 236,
        "11" : 577
      },
      "bg" : {
        "10" : 15501,
        "6" : 1931,
        "4" : 689,
        "2" : 725,
        "7" : 6504,
        "11" : 15878
      },
      "fg" : {
        "7" : 137056,
        "3" : 3069,
        "11" : 334589,
        "4" : 14555,
        "1" : 505774,
        "6" : 40718,
        "2" : 15294,
        "10" : 326637
      },
      "total" : {
        "7" : 143797,
        "3" : 3069,
        "11" : 351045,
        "4" : 15270,
        "1" : 505774,
        "6" : 42720,
        "2" : 16046,
        "10" : 342702
      }
    },
    "app_time" : {
      "GPU" : 503,
      "CPU" : 2479,
      "bg_unplugged" : {
        "audio" : 6,
        "location_audio" : 0,
        "total" : 171,
        "location" : 0
      },
      "fg_total" : 3492,
      "fg_unplugged" : 3492,
      "cellular_condition" : {
        "signalBarUnknown" : 0,
        "signalBar1" : 91,
        "signalBar0" : 0,
        "signalBar4" : 2282,
        "signalBar3" : 1060,
        "signalBar2" : 341
      },
      "bg_total" : {
        "audio" : 6,
        "location_audio" : 0,
        "total" : 171,
        "location" : 0
      }
    }
  },

The key 10, 6, 4, 2, 7, 11 means what?

    "10" : 563,
    "6" : 70,
    "4" : 25,
    "2" : 26,
    "7" : 236,
    "11" : 577