{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "$id": "https://raw.githubusercontent.com/zarr-conventions/proj/refs/tags/v0.1/schema.json",
  "title": "Geospatial Projection Convention (proj)",
  "description": "Schema for geospatial coordinate reference system information in Zarr. Properties use the 'proj:' namespace prefix.",
  "type": "object",
  "properties": {
    "zarr_format": {
      "type": "integer",
      "description": "Zarr format version"
    },
    "node_type": {
      "type": "string",
      "enum": ["array", "group"],
      "description": "Type of Zarr node"
    },
    "attributes": {
      "type": "object",
      "description": "Zarr attributes containing convention metadata and proj: prefixed properties",
      "properties": {
        "zarr_conventions": {
          "type": "array",
          "description": "Array of convention metadata objects",
          "contains": {
            "$ref": "#/$defs/conventionMetadata"
          }
        }
      },
      "required": ["zarr_conventions"],
      "$ref": "#/$defs/projAttributes"
    }
  },
  "required": ["zarr_format", "node_type", "attributes"],
  "additionalProperties": true,
  "$defs": {
    "conventionMetadata": {
      "type": "object",
      "description": "Geospatial projection convention metadata object for use in zarr_conventions array",
      "properties": {
        "schema_url": {
          "type": "string",
          "const": "https://raw.githubusercontent.com/zarr-conventions/proj/refs/tags/v0.1/schema.json",
          "description": "URL to the JSON Schema definition for this convention"
        },
        "spec_url": {
          "type": "string",
          "const": "https://github.com/zarr-conventions/proj/blob/v0.1/README.md",
          "description": "URL to the full specification document"
        },
        "uuid": {
          "type": "string",
          "const": "f17cb550-5864-4468-aeb7-f3180cfb622f",
          "description": "UUID that permanently identifies this convention"
        },
        "name": {
          "type": "string",
          "const": "proj",
          "description": "Human-readable name of the convention"
        },
        "description": {
          "type": "string",
          "const": "Coordinate reference system information for geospatial data",
          "description": "Brief description of the convention's purpose and usage"
        }
      },
      "anyOf": [
        {
          "required": ["schema_url"]
        },
        {
          "required": ["spec_url"]
        },
        {
          "required": ["uuid"]
        }
      ],
      "additionalProperties": false
    },
    "projAttributes": {
      "type": "object",
      "description": "Geospatial projection properties using proj: key prefix. For spatial coordinate information (bbox, transform, shape, dimensions), compose with the spatial: convention.",
      "properties": {
        "zarr_conventions": true,
        "proj:code": {
          "type": "string",
          "description": "CRS authority:code identifier (e.g., EPSG:4326, EPSG:32633)",
          "pattern": "^[^:]+:[^:]+$"
        },
        "proj:wkt2": {
          "type": "string",
          "description": "WKT2 (ISO 19162:2019) CRS representation"
        },
        "proj:projjson": {
          "$ref": "https://proj.org/schemas/v0.7/projjson.schema.json",
          "description": "PROJJSON CRS representation following PROJ specification"
        }
      },
      "anyOf": [
        {
          "required": ["proj:code"]
        },
        {
          "required": ["proj:wkt2"]
        },
        {
          "required": ["proj:projjson"]
        }
      ],
      "additionalProperties": true
    }
  }
}