Schema: Possible type error in image-photometric-calibration.photometric-sequence-illumination-type

The description of image-photometric-calibration.photometric-sequence-illumination-type suggests that this field could be an enum instead of string.

"image-photometric-calibration": {
                    "description": "Information required to specify the photometric calibration. Details given in properties.",
                    "type": "object",
                    "properties": {
                        [...],
                        "photometric-sequence-illumination-type": {
                            "description": "e.g. constant artificial, globally adapted artificial, individually varying light sources, sunlight, mixed)",
                            "type": "string"
                        },
                       [...]
                    }
                },