@openstreetmap/id-tagging-schema/data/fields/railway/signal_box.json

The OpenStreetMap tagging model used by the iD editor

{
    "key": "railway:signal_box",
    "type": "combo",
    "label": "Type",
    "strings": {
        "options": {
            "mechanical": "Mechanical",
            "electric": "Electrical",
            "track_diagram": "Digital",
            "electronic": "Fully Automated"
        }
    },
    "autoSuggestions": false,
    "customValues": false
}