Clarifications to Deployment and additional rationale.

Co-authored-by: Jack Grigg <jack@electriccoin.co>
Signed-off-by: Daira Hopwood <daira@jacaranda.org>

zip-0317.rst

@@ -20,8 +20,8 @@
 Terminology
 ===========
 
-The key word "SHOULD" in this document is to be interpreted as described in
+The key words "SHOULD" and "SHOULD NOT" in this document are to be interpreted
-RFC 2119. [#RFC2119]_
+as described in RFC 2119. [#RFC2119]_
 
 The term "conventional transaction fee" in this document is in reference
 to the value of a transaction fee that is conventionally used by wallets,
@@ -36,7 +36,8 @@ Abstract
 ========
 
 The goal of this ZIP is to change the conventional fees for transactions
-and get buy-in from wallet developers, miners, and Zcash users.
+by making them dependent on the number of inputs and outputs in a transaction,
+and to get buy-in for this change from wallet developers, miners and Zcash users.
 
 
 Motivation
@@ -231,6 +232,12 @@ previously used the conventional transaction fee defined in ZIP 313 to
 decide on transaction inclusion, it is expected to instead use the formula
 specified in this ZIP.
 
+Miners have an incentive to make this change because:
+
+* it will tend to increase the fees they are due;
+* fees will act as a damping factor on the time needed to process blocks,
+  and therefore on orphan rate.
+
 
 Security and Privacy considerations
 ===================================
@@ -270,12 +277,15 @@ Wallets SHOULD deploy these changes immediately. Nodes SHOULD deploy the
 change to the :math:`low\_fee\_penalty` threshold described in
 `Mempool size limiting`_ immediately.
 
-Nodes can deploy restrictions to their policies for relaying, mempool
+Miners can deploy restrictions to their policies for transaction inclusion,
-acceptance, and/or mining once a sufficient proportion of wallets in the
+once a sufficient proportion of wallets in the ecosystem are observed to
-ecosystem are observed to be paying at least the updated conventional
+be paying at least the updated conventional transaction fee.
-transaction fee. Node developers SHOULD coordinate on deployment
-schedule.
 
+Node developers SHOULD coordinate on schedules for deploying restrictions
+to their policies for transaction mempool acceptance and peer-to-peer
+relaying. These policy changes SHOULD NOT be deployed before the changes
+to transaction inclusion policy by miners described in the preceding
+paragraph.
 
 
 Considered Alternatives
@@ -283,6 +293,10 @@ Considered Alternatives
 
 This section describes alternative proposals that have not been adopted.
 
+In previous iterations of this specification, the marginal fee was multiplied
+by the sum of inputs and outputs. This means that the alternatives given
+below are roughly half of what they would be under the current formula.
+
 Possible alternatives for the parameters:
 
 * marginal_fee = 250 in @nuttycom's proposal.
@@ -306,8 +320,9 @@ updated fee mechanism:
 
 *Developer Groups or Sole OSS contributors*
 
-* Zecwallet Suite (Zecwallet Lite for Desktop/iOS/Android & Zecwallet FullNode)
+..
-* Nighthawk Wallet for Android & iOS
+  * Zecwallet Suite (Zecwallet Lite for Desktop/iOS/Android & Zecwallet FullNode)
+  * Nighthawk Wallet for Android & iOS
 
 To express and request your support to be added to this ZIP please comment
 below indicating:
@@ -318,9 +333,9 @@ below indicating:
 
 or, conversely e-mail the same details to the Owner of the ZIP.
 
-> TODO: Endorsements may depend on specific parameter choices. The ZIP
+TODO: Endorsements may depend on specific parameter choices. The ZIP
-> Editors should ensure that the endorsements are accurate before merging
+Editors should ensure that the endorsements are accurate before merging
-> this ZIP.
+this ZIP.
 
 
 Acknowledgements