Nsm specify social constraints on reissuance

zips/zip-0233.md

@@ -54,9 +54,10 @@ This ZIP proposes the introduction of a mechanism to voluntarily remove funds
 entirely from circulation on the network. The explicit intent of this removal
 is that the funds will be returned to circulation through future block subsidies,
 rather than being permanently destroyed or held in reserve for discretionary use.
-This mechanism, in combination with ZIP 234 and ZIP 235 [^zip-0235], comprises a
-long-term strategy for the sustainability of the network. We will refer to the
-combined effects of these three ZIPs as the “Network Sustainability Mechanism”.
+This mechanism, in combination with ZIP 234 [^zip-0234] and ZIP 235 [^zip-0235],
+comprises a long-term strategy for the sustainability of the network. We will
+refer to the combined effects of these three ZIPs as the “Network Sustainability
+Mechanism”.
 
 
 # Motivation
@@ -78,6 +79,17 @@ design shared by Bitcoin-like systems:
    an increase in the value of remaining ZEC, it can be argued to benefit network
    users in proportion to their holdings — without requiring them to opt into any
    scheme, introducing extra risk, active oversight, or accounting complexity.
+3. **Enable Neutral Contributions to The Future of the Network Itself:** Funds
+   removed with this mechanism are intented for future reissuance on a long time
+   scale, which enables donors or protocol fees to contribute to the network's
+   future in general, without any preference or bias to any participants.
+4. **Enable Neutral Costly Signaling:** Any funds removed with this mechanism will
+   be distributed in a neutral manner in the future, which enables donors or
+   protocol features to provide a "costly signal". This can be useful for a
+   variety of purposes, including ensuring miners are not "padding" blocks with
+   transaction fees at 0 cost, Sibyl resistance in pseudonymous protocols
+   anchored on the Zcash ledger, ensuring a donor isn't surreptitiously
+   benefiting from their donation, and so on.
 
 # Privacy Implications
 
@@ -91,6 +103,37 @@ the privacy properties of shielded funds.
 - The mechanism enables users to remove funds from the circulating supply, and each removal event is explicitly specified in the corresponding transaction.
 - The process is publicly auditable, allowing network participants to verify the amount and occurrence of funds removed from circulation.
 
+## Use of Funds Restrictions
+
+This ZIP was designed specifically in concert with ZIP 234 [^zip-0234] and ZIP
+235 [^zip-0235]. During the review and consensus building around these three
+ZIPs, several alternatives have been proposed, including deploying ZIP 234 later
+or replacing ZIP 234 with an alternative reissuance algorithm.
+
+If this ZIP 233 is deployed without the accompanying ZIP 234 at the same time,
+it is important to that users of this ZIP 233 feature have clarity about the use
+of any ZEC removed with this mechanism. We only support this ZIP along with any
+alternative so long as these guarantees are upheld:
+
+- The complete design of the Zcash protocol including this ZIP and any
+  companions cannot result in more than $MAX_MONEY$ circulating ZEC at any time.
+- The rate of re-issuance of all ZEC removed via this mechanism _MUST NOT_
+  exceed an exponential decay rate with a 4 year half-life in any given
+  interval, as reasonably approximated by the consensus protocol. Note that this
+  is more strict than the BTC issuance schedule which fails to meet this
+  condition except for time intervals greater than dozens of years.
+- The re-issued ZEC must be added directly to the general block rewards without
+  affecting the recipients of those rewards or their relative proportions.
+
+It's worth pointing out that these conditions would be met by never re-issuing
+the funds or by ZIP 234, although alternative designs are also possible.
+Furthermore, it's worth reviewing the ZIP 234 Requirements section for any
+alternatives.
+
+The rationale for these restrictions is to uphold both the supply cap integrity
+and also a precise rate-limit on re-issuance to ensure predictability and a long
+time horizon for the effects of reissuance.
+
 # Specification
 
 ## Transaction Field