API : What do the 2nd numbers refer to for connected inputs?

[caniyabanci76]

in the API output we have something like the following for the VAEDecode node :

  "8": {
    "inputs": {
      "samples": [
        "3",
        0
      ],
      "vae": [
        "4",
        2
      ]
    },
    "class_type": "VAEDecode"
  },

for samples and vae, I understand that the first number strings "3", "4" refer to the node IDs that they connected to, but what is the secondary number? (in this case 0 and 2) ?

[ltdrdata]

2nd number is slot number