Subject: Re: [Bitcoin-development] BIP 70 refund field

From: Tamas Blummer <[email-masked]>
Date: Fri, 28 Mar 2014 14:09:34 +0100

On 28.03.2014, at 14:00, Mike Hearn <[email-masked]> wrote:

> What is too abstract in a contact list ? If the payment comes with a tag like refund the UI could display as such and if it comes with e.g. VAT then that. 
> 
> How is this any different? The tag in this case is the address and the payment is being delivered by the block chain (direct submission for user->merchant is easier than merchant->user) so we can't stuff extra data anywhere else. Then the UI knows it was a refund payment and not for anything else.
> 

The difference is the concept of setting up a channel that allows both parties to create valid addresses of the other by exchanging some kind of master keys. The initial handshake with the protocol would agree on tags of individual address indexes if used. The wallets would have to observe those agreed inidices and evtl. extend range. Payments could go back and forth. Either party might delete the channel information and stop observing keys as soon as he does no longer expect a payment from the other. This would be an explicit operation, like deleting a contact.

> I don't see the relevance of VAT here.

It was an example label. I would not be suprised if with widespread use of payments some government would require VAT collected separately. It is just a guess and has no weight in my prior arguments.