@openstreetmap/id-tagging-schema/data/fields/building/levels_building.json

The OpenStreetMap tagging model used by the iD editor

{
    "key": "building:levels",
    "type": "number",
    "minValue": 0,
    "label": "{building/levels}",
    "placeholder": "{building/levels}",
    "prerequisiteTag": {
        "key": "building",
        "valueNot": "no"
    }
}