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On Mon, 5 Dec 2022 11:53:11 -0800
Chris Brandson via tcpdump-workers <tcpdump-workers@lists.tcpdump.org>

> Hello everyone,
> We are pleased to publish the draft Z-Wave G.9959 TAP Specification

Hello Chris.

Thank you for preparing the document.  I am not familiar with the
standard to make more substantial comments, but a few things seem to
require some attention:

* Page 7: "Length is a minimum of 4 octets and must be a multiple of 4.
  The addition of new TLVs does not and must not require incrementing
  the version number." -- this definition automatically creates a
  problem space on the receiving/reading end of this encoding because
  slightly more than 75% of all possible length values are invalid by
  definition. The classic solution would be not to include the first 4
  octets into the length, and to count in multiples of 4, this way any
  length value would be valid, free of underflows and better consumable
  by simple parsers such as BPF bytecode.

* Page 8: "Z-Wave PHY Payload" -- is this the PPDU from Figure A.7 of
  G.9959 2015/01, starting from "preamble sequence"?

* Page 9: "length - number of octets for type in value field (not
  including padding)" -- this definition looks better, but in the next
  three TLV diagrams the length does include the T and the L.

* Page 10: If the list of region code points is a copy/subset of an
  external registry, it would help to give an exact reference.  Ditto
  bit rate code points.  Clearly there is some relation with tables A.1
  and A.2 from G.9959 2015/01.

    Denis Ovsienko

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