Evaluate if `spatial` field is fit for ontological use

[chrwm]

Description of the issue

In the oeo-dev meeting 63 geographical regions and their incorporation into the OEO were discussed.

• [ ] check if current metadata can represent annotation solution from oeo-dev meeting

"spatial": {
        "location": null,
        "extent": "europe",
        "resolution": "100 m"

Ideas of solution

Describe possible ideas for solution and evaluate advantages and disadvantages.

Workflow checklist

• [ ] I am aware of the workflow in CONTRIBUTING.md