Thanks for your email Peter!

On Tuesday 20 Sep 2016 17:56:44 Peter Todd wrote:
> On Tue, Sep 20, 2016 at 07:15:45PM +0200, Tom via bitcoin-dev wrote:
> > === Serialization order===
> > 
> > The tokens defined above have to be serialized in a certain order for the
> > transaction to be well-formatted.  Not serializing transactions in the
> > order specified would allow multiple interpretations of the data which
> > can't be allowed.
> 
> If the order of the tokens is fixed, the tokens themselves are redundant
> information when tokens are required; when tokens may be omitted, a simple
> "Some/None" flag to mark whether or not the optional data has been omitted
> is appropriate.

This is addressed in the spec; 
https://github.com/bitcoinclassic/documentation/blob/master/spec/transactionv4.md

«The way towards that flexibility is to use a generic concept made popular
various decades ago with the XML format. The idea is that we give each
field a name and this means that new fields can be added or optional fields
can be omitted from individual transactions»


> Also, if you're going to break compatibility with all existing software, it
> makes sense to use a format that extends the merkle tree down into the
> transaction inputs and outputs.

Please argue your case.