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

The OpenStreetMap tagging model used by the iD editor

{
    "key": "start_date",
    "type": "date",
    "universal": true,
    "label": "Start Date",
    "placeholder": "YYYY-MM-DD",
    "terms": [
        "inception"
    ]
}