{
    "$schema": "http://json-schema.org/draft-07/schema#",
    "$id": "https://openindexmaps.org/openindexmap.schema.json",
    "title": "OpenIndexMap",
    "description": "Describes an OpenIndexMap according to specification version 1.0.0.",
    "type": "object",
    "definitions": {
        "Geometry": {
            "type": "object",
            "properties": {
                "type": {
                    "enum": ["Point", "LineString", "Polygon", "MultiPoint", "MultiLineString", "MultiPolygon", "GeometryCollection"]
                },
                "coordinates": {
                    "type": "array",
                    "items": {}
                },
                "geometries": {
                    "type": "array",
                    "items": {
                        "$ref": "#/definitions/Geometry"
                    }
                }
            },
            "required": ["type", "coordinates"]
        }
    },
    "properties": {
        "type": {
            "enum": [
                "FeatureCollection"
            ]
        },
        "features": {
            "type": "array",
            "items": {
                "type": "object",
                "properties": {
                    "type": {
                        "enum": [
                            "Feature"
                        ]
                    },
                    "geometry": {
                        "type": "object",
                        "$ref": "#/definitions/Geometry"
                    },
                    "properties": {
                        "type": "object",
                        "additionalProperties": true,
                        "patternProperties": {
                            "^[a-z][a-zA-Z0-9]{0,9}$": {},
                            "^[a-z][a-zA-Z0-9]*[A-Z]{2,}[a-zA-Z0-9]*$": {
                                "not": {},
                                "errorMessage": "Property names cannot have two consecutive uppercase letters."
                            },
                            "^.{11,}$": {
                                "not": {},
                                "errorMessage": "Property names cannot be longer than 10 characters."
                            }
                        },
                        "properties": {
                            "label": {
                                "type": [
                                    "string",
                                    "null"
                                ],
                                "description": "Alphanumeric code identifying the sheet or frame. The value of this field is used as a tool tip in GeoBlacklight."
                            },
                            "labelAlt": {
                                "type": [
                                    "string",
                                    "null"
                                ],
                                "description": "Alphanumeric code for the sheet or frame that was used for previous or subsequent editions, or for when there are multiple labels."
                            },
                            "labelAlt2": {
                                "type": [
                                    "string",
                                    "null"
                                ],
                                "description": "Alphanumeric code for the sheet or frame when there are multiple labels."
                            },
                            "datePub": {
                                "type": [
                                    "string",
                                    "null"
                                ],
                                "description": "The date that the sheet or frame was published or made available."
                            },
                            "date": {
                                "type": [
                                    "string",
                                    "null"
                                ],
                                "description": "Used when no other date field is relevant."
                            },
                            "west": {
                                "type": [
                                    "number",
                                    "null"
                                ],
                                "description": "Farthest west extent of the sheet/frame bounding box (using the Greenwich Meridian)."
                            },
                            "east": {
                                "type": [
                                    "number",
                                    "null"
                                ],
                                "description": "Farthest east extent of the sheet/frame bounding box (using the Greenwich Meridian)."
                            },
                            "north": {
                                "type": [
                                    "number",
                                    "null"
                                ],
                                "description": "Farthest north extent of the sheet/frame bounding box."
                            },
                            "south": {
                                "type": [
                                    "number",
                                    "null"
                                ],
                                "description": "Farthest south extent of the sheet/frame bounding box."
                            },
                            "location": {
                                "type": [
                                    "array",
                                    "null"
                                ],
                                "items": {
                                    "type": [
                                        "string",
                                        "null"
                                    ]
                                },
                                "description": "Geographic place name identifying the area covered by the map sheet or air photo frame."
                            },
                            "scale": {
                                "type": [
                                    "string",
                                    "null"
                                ],
                                "description": "Scale statement (representative fraction plus qualifiers) of the individual sheet/frame."
                            },
                            "color": {
                                "type": [
                                    "string",
                                    "null"
                                ],
                                "description": "Indicates whether the sheet/frame is color, black and white, color infrared or another color type."
                            },
                            "title": {
                                "type": [
                                    "string",
                                    "null"
                                ],
                                "description": "Title of map, usually a geographic location on that sheet."
                            },
                            "titleAlt": {
                                "type": [
                                    "string",
                                    "null"
                                ],
                                "description": "Alternate title for the sheet that was used for previous or subsequent editions, or for when there are multiple titles."
                            },
                            "dateSurvey": {
                                "type": [
                                    "string",
                                    "null"
                                ],
                                "description": "Date that the map sheet was surveyed."
                            },
                            "datePhoto": {
                                "type": [
                                    "string",
                                    "null"
                                ],
                                "description": "Date that the map sheet was photocorrected."
                            },
                            "dateReprnt": {
                                "type": [
                                    "string",
                                    "null"
                                ],
                                "description": "Date that the map sheet was reprinted."
                            },
                            "overprint": {
                                "type": [
                                    "string",
                                    "null"
                                ],
                                "description": "no description given"
                            },
                            "edition": {
                                "type": [
                                    "string",
                                    "null"
                                ],
                                "description": "Statement indicating the edition of the map sheet."
                            },
                            "publisher": {
                                "type": [
                                    "string",
                                    "null"
                                ],
                                "description": "Publisher of the individual sheet (can be used if publishers vary within a map set)."
                            },
                            "overlays": {
                                "type": [
                                    "string",
                                    "null"
                                ],
                                "description": "no description given"
                            },
                            "projection": {
                                "type": [
                                    "string",
                                    "null"
                                ],
                                "description": "The map’s or photo’s projection, coordinate system and datum."
                            },
                            "lcCallNo": {
                                "type": [
                                    "string",
                                    "null"
                                ],
                                "description": "Library of Congress call number."
                            },
                            "contLines": {
                                "type": [
                                    "boolean",
                                    "null"
                                ],
                                "description": "Indication of whether or not there are contour lines on the map."
                            },
                            "contInterv": {
                                "type": [
                                    "string",
                                    "null"
                                ],
                                "description": "Distance between contour lines. Include unit (or abbreviation)."
                            },
                            "bathLines": {
                                "type": [
                                    "boolean",
                                    "null"
                                ],
                                "description": "Indication of whether or not there are bathymetric contour lines on the map."
                            },
                            "bathInterv": {
                                "type": [
                                    "string",
                                    "null"
                                ],
                                "description": "Distance between bathymetric contour lines. Include unit (or abbreviation)."
                            },
                            "primeMer": {
                                "type": [
                                    "string",
                                    "null"
                                ],
                                "description": "Indicates a prime meridian other than Greenwich."
                            },
                            "photomos": {
                                "type": [
                                    "boolean",
                                    "null"
                                ],
                                "description": "Indication that the image is a mosaic of several air photos."
                            },
                            "bands": {
                                "type": [
                                    "string",
                                    "null"
                                ],
                                "description": "Spectral bands present (near infrared, red, green, blue, etc.)."
                            },
                            "rectificn": {
                                "type": [
                                    "string",
                                    "null"
                                ],
                                "description": "Any corrections done to adjust the air photo image."
                            },
                            "rollNo": {
                                "type": [
                                    "string",
                                    "null"
                                ],
                                "description": "Identifier for the film reel from which the air photo comes."
                            },
                            "inst": {
                                "type": [
                                    "string",
                                    "null"
                                ],
                                "description": "Local institution holding material."
                            },
                            "sheetId": {
                                "type": [
                                    "string",
                                    "null"
                                ],
                                "description": "Local institution’s unique identifier for the sheet/frame."
                            },
                            "available": {
                                "type": [
                                    "boolean",
                                    "null"
                                ],
                                "description": "Indication if the institution holds the item at this location in any format."
                            },
                            "physHold": {
                                "type": [
                                    "string",
                                    "null"
                                ],
                                "description": "Indication if the institution holds the item in a physical format, or a link to information about the physical object."
                            },
                            "digHold": {
                                "type": [
                                    "string",
                                    "null"
                                ],
                                "description": "Indication if the institution holds the item in a digital format, or a link to information about the digital object, or a link to the digital object itself."
                            },
                            "instCallNo": {
                                "type": [
                                    "string",
                                    "null"
                                ],
                                "description": "Call number used locally (other than Library of Congress call number)."
                            },
                            "recId": {
                                "type": [
                                    "string",
                                    "null"
                                ],
                                "description": "Local institution’s unique identifier for the digital object."
                            },
                            "download": {
                                "type": [
                                    "string",
                                    "null"
                                ],
                                "format": "uri",
                                "description": "Link used to directly download the digital object."
                            },
                            "websiteUrl": {
                                "type": [
                                    "string",
                                    "null"
                                ],
                                "format": "uri",
                                "description": "Link used to direct users to a website with metadata or a download link for the digital object."
                            },
                            "thumbUrl": {
                                "type": [
                                    "string",
                                    "null"
                                ],
                                "format": "uri",
                                "description": "Link used to access the thumbnail for the digital object."
                            },
                            "iiifUrl": {
                                "type": [
                                    "string",
                                    "null"
                                ],
                                "format": "uri",
                                "description": "Link used to access the digital image using IIIF."
                            },
                            "fileName": {
                                "type": [
                                    "string",
                                    "null"
                                ],
                                "description": "Digital file associated with sheet/frame."
                            },
                            "note": {
                                "type": [
                                    "string",
                                    "null"
                                ],
                                "description": "Free text for local comments as well as general notes applying to everyone’s copy."
                            }
                        }
                    }
                },
                "required": [
                    "type",
                    "geometry",
                    "properties"
                ]
            }
        }
    },
    "not": {
        "required": ["properties"]
    }
}