[bitcoin-dev] Requesting BIP assignment; Flexible Transactions.

[Tom]

On Friday, 23 September 2016 13:55:50 CEST Christian Decker via bitcoin-dev 
wrote: 
> Not sure if the comparison to XML and HTML holds: the lack of closing
> tags makes the meaning of individual tokens ambiguous, like I pointed
> out before. The use of segments gives at most two levels of nesting,
> so any relationship among tokens in the same segment has to rely on
> their relative position, which could result in ambiguities, like
> whether a tag refers to a single input or the transaction as a whole.


Practically all tagged formats make ordering a requirement, so indeed this 
is relevant, and not unique.

For instance if you write;
  <div> Some line </br>Another line</br>3rd line</div>
you can get a good idea of how ordering is relevant. You can reuse any item 
many times.

Whenever there is a possible confusion the specification specifically 
explains which order to use.

I'm not sure what you mean with the idea this;

>  The use of segments gives at most two levels of nesting

It looks like you assume there is some opening and closing tags, since 
otherwise there would be no nesting.
Such tags are not intended, nor documented.

> so any relationship among tokens in the same segment has to rely on
> their relative position, which could result in ambiguities, like
> whether a tag refers to a single input or the transaction as a whole.

I quoted parts of the spec in your previous email stating the same thing, 
but I'll repeat here.
Any place that has any sort of possibility to be ambiguous is specified 
specifically to have an order.  This makes writing and parsing easier.

Since you wrote two emails now with the same issue, and I addressed it 
twice, I would urge you to write out some examples which may be confusing 
and if you find that the spec is indeed missing requirements then please 
share it with us.  I did this some time ago and it helps understanding the 
ideas by having actual explicit examples.  I am not aware of any sort of 
ambiguities that the spec allows.

Cheers!