@openstreetmap/id-tagging-schema/data/fields/level.json

The OpenStreetMap tagging model used by the iD editor

{
    "key": "level",
    "type": "combo",
    "label": "Level",
    "terms": [
        "building floor",
        "deck",
        "storey",
        "story"
    ],
    "prerequisiteTag": {
        "keyNot": "building"
    }
}