simon@nirvana ~/Work/ubuntu/snappy/hwe/images $ cat pi3.json 
{
  "type": "model",
  "authority-id": "canonical",
  "brand-id": "canonical",
  "series": "16",
  "model": "pi3",
  "architecture": "armhf",
  "gadget": "pi3",
  "kernel": "pi2-kernel"
}