network_key read and write takes extra byte

[stuart]

Whilst implementing this in Elixir/Erlang I found that Read Parameter Request frames frames for the network key parameter required an extra 0x00 byte after the parameter_id in order to return a value. The value returned also had the extra byte, that is the payload had 17 bytes not 16 as per the document.

The Write Parameter Request also required the extra byte or the response was invalid value.

Is there a quirk where the parameter id treated as a u16 in this case or is the data padded with an extra byte?