type: map
mapping: 
  "protocol": 
    type:     map
    required: yes
    mapping: 
      "name": 
        type: str
        required: yes
      "longname": 
        type: str
      "fields": 
        type: seq
        required: yes
        sequence: &fieldsseq
          - type: map
            mapping: 
              "field": #field name (best if only one word, for easier referencing)
                type: str
                required: yes
              "desc": #short description
                type: str
              "length": #length in bytes, except bitfield is set to true!
                type: int
              "bitfield": #if this is true length is in BITS!
                type: bool
              "optional":
                type: bool
              "repeatable":
                type: bool
              "nextlayer": #identifies this field as nextlayer field (see nextlayer definition below)
                type: bool
              "data": #data placeholder for next layer
                type: bool
              "reference": #reference another protocol directly (e.g. ethpacket->ethframe) 
                type: str
              "reflength": #reference another field for length of this field
                type: str
              "subfields": 
                type: seq
                sequence: *fieldsseq
      "osilayer": 
        type: int 
        range: { max: 7, min: 1 }
        required: yes
      "extensionreferencefield":
        type: str
      "extensions": 
        type: seq
        sequence: 
          - type: map
            mapping: 
              "extension": &extension
                type: map
                mapping: 
                  "name":
                    type: str
                    required: yes
                  "referencedfrom": #referencing field of protocol definition
                    type: str
                  "referenceid": #reference id used in protocol definition or extension itself
                    type: int
                    required: yes #really? maybe not...
                  "before": # standard is after the normal protocol structure, but could be used for vlan in ethernet for example.
                    type: str
                  "after": 
                    type: str
                  "fields":
                    type: seq
                    sequence: *fieldsseq
      "documentation": 
        type: map
        mapping:
          "summary": # a summary about this protocol (optional)
            type: str
          "descriptions": # descriptions of the fields
            type: seq
            sequence:
              - type: map
                mapping:
                  "field":  # field name as defined in the protocol structure
                    type: str
                    required: yes
                  "desc":   # description 
                    type: str
                    required: yes
... #kwalify needs this, or it goes crazy validating, but only when there are comments beneath


# constraints

# even possible?
# how to implement?

#maybe like this:
# "constraint":
#   type: map
#   mapping:
#     "name":
#       type: str
#     "type": # hmm, maybe better in triggers with "function": ?
#       enum: [ crc, ...? ]
#     "triggers":
#       type: seq
#       ....
#     "actions":
#       type: seq
#       sequence:
#         - type: map
#           mapping:
#             "extension": *extension