From e2b78a4279c85ef4f7a27aaba456b85e9f0743f4 Mon Sep 17 00:00:00 2001
From: Wei Tang <hi@that.world>
Date: Fri, 21 Jun 2019 05:03:48 +0200
Subject: [PATCH] Change I_a to the code's version

---
 EIPS/eip-1702.md | 51 ++++++++++++++++++++++++++++++++----------------
 1 file changed, 34 insertions(+), 17 deletions(-)

diff --git a/EIPS/eip-1702.md b/EIPS/eip-1702.md
index 588bbc2f784a2..9601c2986831f 100644
--- a/EIPS/eip-1702.md
+++ b/EIPS/eip-1702.md
@@ -48,6 +48,17 @@ items: `nonce`, `balance`, `storageRoot`, `codeHash`, and
 items. When `version` is not zero, the account is RLP-encoded with 5
 items.
 
+### Contract Execution
+
+When fetching an account code from state, we always fetch the
+associated version field together. We refer to this as the *code's
+version* below. The code of the account is always executed in the
+*code's version*.
+
+In particular, this means that for `DELEGATECALL` and `CALLCODE`, the
+version of the execution call frame is the same as
+delegating/receiving contract's version.
+
 ### Contract Deployment
 
 In Ethereum, a contract has a deployment method, either by a contract
@@ -58,7 +69,7 @@ transaction.
 
 We let a family of contracts to always have the same `version`. That
 is, `CREATE` and `CREATE2` will always deploy contract that has the
-same `version` as the calling `address`.
+same `version` as the *code's version*.
 
 ### Validation
 
@@ -71,18 +82,14 @@ that has to be passed.
 If the validation phrase fails, deployment does not proceed and return
 out-of-gas.
 
-### Contract Execution
-
-VM version used in contract execution is determined via calling
-`address` (`I_a` in yellow paper).
-
 ### Contract Creation Transaction
 
 Define `LATEST_VERSION` in a hard fork to be the latest supported VM
 version. A contract creation transaction is always executed in
-`LATEST_VERSION`. Before a contract creation transaction is executed,
-run *validation* on the contract creation code. If it does not pass,
-return out-of-gas.
+`LATEST_VERSION` (which means the *code's version* is
+`LATEST_VERSION`), and deploys contracts of `LATEST_VERSION`. Before a
+contract creation transaction is executed, run *validation* on the
+contract creation code. If it does not pass, return out-of-gas.
 
 ### Precompiled Contract and Externally-owned Address
 
@@ -112,14 +119,23 @@ prefix (for example, `\0asm`) to `version` number. All version
 prefixes have the invariant that given any prefix in mapping `a` and
 `b`, `a` is not `b`'s prefix. Version numbers in `V` cannot be zero.
 
+For contract deployment transaction, run the following additional
+steps.
+
+* Check that the code starts with an prefix in `V`, with `version`
+  number.
+* Use `version`'s validation procedure to validate the *whole* code
+  (with prefix).
+* Execute the code with the *code's version* being `version`.
+* Apply the deployment routine defined as below.
+
 Apply the following cause on contract deployment for all `CREATE`,
-`CREATE2` and contract deployment transaction.
+`CREATE2` and contract deployment transaction's deployment phrase.
 
-* If the `version` of caller (determined by `I_a`) is zero, then
-  `CREATE` and `CREATE2` will always deploy contract with version zero.
-* If the `version` of caller (determined by `I_a`) is not zero, do the
-  following checks and operations, and return out-of-gas if any of it
-  fails:
+* If the *code's version* is zero, then `CREATE` and `CREATE2` will
+  always deploy contract with version zero.
+* If the *code's version* is not zero, do the following checks and
+  operations, and return out-of-gas if any of it fails:
   * Check that the code starts with an prefix in `V`, with `version`
     number.
   * Use `version`'s validation procedure to validate the *whole* code
@@ -149,8 +165,9 @@ creation transaction. So it becomes `nonce`, `gasprice`, `startgas`,
 `to`, `value`, `data`, `v`, `r`, `s`, `version`. When signing or
 recovering, sign ten items, with `v`, `r`, `s` as defined by EIP-155.
 
-The transaction would be executed in `version` supplied. If `version`
-is not supported or *validation* does not pass, return out-of-gas.
+The transaction would be executed with the *code's version* in
+`version` supplied, and deploys contract of `version`. If `version` is
+not supported or *validation* does not pass, return out-of-gas.
 
 ### Extending `CREATE` and `CREATE2`