Replying to the "fee" part of BIP75 (which as already noted should go to
a different BIP number imho):

It makes to sense to let the payee define a fee *rate*. The payee
doesn't know anything about how the payer's wallet is structured. In
extreme cases, as a payer I would keep all my tiny UTXOs (which would be
unspendable in a economic way) for the one payee who is willing to pay a
high enough rate...

Rather, I propose an absolute amount that the payee is willing to cover
should be declared.

Also, in order to avoid disputes I suggest the amount should be deducted
from the BIP70 payment message amount already. A wallet which
understands BIP75fee would add these two up for *display* puposes only.
The wallet should continue to use the existing fee policies. If it can
send the amount as specified by BIP70 and the fee is below the BIP75fee
amount, it would not mention any fees to the user. If it exceeds, it
would display just the exceeding amount.




On 03/11/2016 11:43 PM, Justin Newton via bitcoin-dev wrote:
> I think we would be open to either leaving them in, or doing a separate
> BIP.  What do others think?  I’d prefer to keep them together if the
> changes are non-controversial just to cut down on #of BIP’s, but thats
> not a strong preference.
>
> On Fri, Mar 11, 2016 at 3:54 AM, Andreas Schildbach via bitcoin-dev
> <bitcoin-dev@lists.linuxfoundation.org
> <mailto:bitcoin-dev@lists.linuxfoundation.org>> wrote:
>
>     I think it's a bad idea to pollute the original idea of this BIP with
>     other extensions. Other extensions should go to separate BIPs,
>     especially since methods to clarify the fee have nothing to do with
>     secure and authenticated bi-directional BIP70 communication.
>
>
>     On 03/10/2016 10:43 PM, James MacWhyte via bitcoin-dev wrote:
>     > Hi everyone,
>     >
>     > Our BIP (officially proposed on March 1) has tentatively been assigned
>     > number 75. Also, the title has been changed to "Out of Band Address
>     > Exchange using Payment Protocol Encryption" to be more accurate.
>     >
>     > We thought it would be good to take this opportunity to add some
>     > optional fields to the BIP70 paymentDetails message. The new
>     fields are:
>     > subtractable fee (give permission to the sender to use some of the
>     > requested amount towards the transaction fee), fee per kb (the minimum
>     > fee required to be accepted as zeroconf), and replace by fee
>     (whether or
>     > not a transaction with the RBF flag will be accepted with zeroconf). I
>     > know it doesn't make much sense for merchants to accept RBF with
>     > zeroconf, so that last one might be used more to explicitly refuse RBF
>     > transactions (and allow the automation of choosing a setting based on
>     > who you are transacting with).
>     >
>     > I see BIP75 as a general modernization of BIP70, so I think it
>     should be
>     > fine to include these extensions in the new BIP, even though these
>     > fields are not specific to the features we are proposing. Please
>     take a
>     > look at the relevant section and let me know if anyone has any
>     concerns:
>     >
>     https://github.com/techguy613/bips/blob/master/bip-0075.mediawiki#Extending_BIP70_PaymentDetails
>     >
>     > The BIP70 extensions page in our fork has also been updated.
>     >
>     > Thanks!
>     >
>     > James
>     >
>     >
>     > _______________________________________________
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>     >
>
>
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>
>
>
> --
>
> Justin W. Newton
> Founder/CEO
> Netki, Inc.
>
> justin@netki.com <mailto:justin@netki.com>
> +1.818.261.4248 <tel:+1.818.261.4248>
>
>
>
>
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