type: map
mapping: 
  "protocol": 
    type:     map
    required: yes
    mapping: 
      "name": 
        type: str
        required: yes
      "fields": 
        type: seq
        required: yes
        sequence: &fieldsseq
          - type: map
            mapping: 
              "field": 
                type: str
                required: yes
              "length": #length in bytes, except bitfield is set to true!
                type: int
                required: yes
              "bitfield": #if this is true length is in BITS!
                type: bool
              "optional":
                type: bool
              "repeatable":
                type: bool
              "data": #data placeholder for next layer (length should be 0!)
                type: bool
              "subfields": 
                type: seq
                sequence: *fieldsseq
      "osilayer": 
        type: int
        range: { max: 7, min: 1 }
        required: yes