type: map
mapping: 
  "layertransition": #layer transition ids
    type: map
    required: yes
    mapping:
      "layers": # which layers?
        type: map
        required: yes
        mapping: 
          "from":
            type: int
            required: yes
          "to":
            type: int
            required: yes
      "protocols": # which protocols support these ids?
        required: yes
        type: seq
        sequence:
          - type: str
            required: yes
      "nextlayer": # list of ids with protocol name (reference name!)
        type: seq
        required: yes
        sequence:
          - type: map
            mapping:
              "idhex": 
                type: str
                required: yes
              "protocol": 
                type: str
                required: yes
              "id":
                type: int