Vcenter REST API VM info - What measure has been used for disk,cdroms identifier

Question

I'm using vcenter REST API to get VM information On Official documentation, each subresource of VM (such as disk, cdrom, sata_adapter....) has their own identifier.But i'm not sure what standard has been used to make those identifier.

Standard json response for VM information is like this

https://developer.vmware.com/apis/vsphere-automation/latest/vcenter/api/vcenter/vm/vm/get/

you can see there are "key" in json response of disks, cdrom, sata_adapter and etcs.... and this is my real json response.

"disks": {
        "2000": {
            "scsi": {
                "bus": 0,
                "unit": 0
            },
            "backing": {
                "vmdk_file": "[datastore3] test.vmdk",
                "type": "VMDK_FILE"
            },
            "label": "Hard disk 1",
            "type": "SCSI",
            "capacity": 322122547200
        },
        "2001": {
            "scsi": {
                "bus": 0,
                "unit": 1
            },
            "backing": {
                "vmdk_file": "[datastore3] ex1.vmdk",
                "type": "VMDK_FILE"
            },
            "label": "Hard disk 2",
            "type": "SCSI",
            "capacity": 17179869184
        },
        "2002": {
            "scsi": {
                "bus": 0,
                "unit": 2
            },
            "backing": {
                "vmdk_file": "[datastore3] ex.vmdk",
                "type": "VMDK_FILE"
            },
            "label": "Hard disk 3",
            "type": "SCSI",
            "capacity": 21474836480
        }
    },
    "parallel_ports": {},
    "sata_adapters": {
        "15000": {
            "bus": 0,
            "pci_slot_number": 33,
            "label": "SATA controller 0",
            "type": "AHCI"
        }
    },

Anyone knows how to measure those numbers at "key" (2000, 2001, 15000) ?

Answer 1

2000  2:0:0:0  
SCSI number (X:X:X:X) 
/sys/class/scsi_device/2:0:0:0/