Draft for the OSMaxx schema description in YAML

OSMaxx_schema.yml

---
layers:
  "geoname_p": &layer_geoname_p
    # == OSMaxx SQL table name == Layer name in exports
    attributes:
      "population":
        type: int
      "wikipedia":
        type: text
      "type":
        type: text
        values:
          "city":
            osm_tags:
              - "place": "city"
            description: >
              The largest urban settlement or settlements within the territory.
          "named_place":
            osm_tags:
              - "area": "yes"
              # Just a string means complete tag (here: name=*)
              # independent of value.
              - "name"
          "place":
            osm_tags:
              # Just a string means complete tag (here: place=*)
              # independent of value.
              - "place"
  "geoname_l": *layer_geoname_p
  "misc_l":
    attributes:
      "type":
        type: text
        values:
          "barrier":
            osm_tags:
              - "barrier"
            correlated_attributes:
              # key: attribute name, value: attribute value
              "aggtype": "barrier"
            description: >
              A barrier is a physical structure which blocks 
              or impedes movement. This contains any other 
              barrier except the specifics below.
          "gate":
            osm_tags:
              - "barrier": "gate"
            correlated_attributes:
              # key: attribute name, value: attribute value
              "aggtype": "barrier"
            description: >
              An entrance that can be opened or closed to 
              get through the barrier.
  "road_ground_l":
    attributes: &layer_road_ground_l_attributes
      "aggtype":
        type: text
        description: >
          Grouping several different 'type' to a common 'type'.
          (aka enmu)
      "ref":
        type: text
        description: >
          Used for reference numbers or codes.
          Common for roads, highway exits, routes, etc.
      "oneway":
        type: boolean
        description: >
          Oneway streets are streets where you are only allowed
          to drive in one direction.
      "maxspeed":
        type: smallint
        description: >
          Specifies the maximum legal speed limit
          on a road, railway or waterway
      "z_order":
        type: smallint
        description: >
          The layer tag is used to describe vertical relationships
          between different crossing or overlapping map features.
          Use this in combination with bridge/tunnel tags when one way
          passes above or under another one. For describing different
          floors within a building or levels of multilevel parking decks
          use levels instead of layers.
      "bridge":
        # can this type be with the specified value ???
        type: boolean
        values:
           "0":
             osm_tags: {}
        description: &road_attribute_bridge_description >
          A bridge is an artificial construction that spans features
          such as roads, railways, waterways or valleys and carries a
          road, railway or other feature.
      "tunnel":
        type: boolean
        values:
          "0":
            osm_tags: {}
        description: &road_attribute_tunnel_description >
          A tunnel is an underground passage for a road or similar.
  "road_bridge_l":
    attributes:
      <<: *layer_road_ground_l_attributes
      "bridge":
        # can this type be with the specified value ???
        type: boolean
        values:
           "1":
             osm_tags:
               "bridge": "yes"
        description: *road_attribute_bridge_description
  "road_tunnel_l":
      <<: *layer_road_ground_l_attributes
      "tunnel":
        # can this type be with the specified value ???
        type: boolean
        values:
           "1":
             osm_tags:
               "tunnel": "yes"
        description: *road_attribute_tunnel_description