merge development

50 files changed, 501 insertions, 260 deletions

diff --git a/packages/contracts/src/2.0.0/extensions/Forwarder/Forwarder.sol b/packages/contracts/src/2.0.0/extensions/Forwarder/Forwarder.sol
index 6b17bb29b..94dec40ed 100644
--- a/packages/contracts/src/2.0.0/extensions/Forwarder/Forwarder.sol
+++ b/packages/contracts/src/2.0.0/extensions/Forwarder/Forwarder.sol
@@ -34,7 +34,6 @@ contract Forwarder is
     MixinExchangeWrapper,
     MixinForwarderCore
 {
-
     constructor (
         address _exchange,
         bytes memory _zrxAssetData,
diff --git a/packages/contracts/src/2.0.0/extensions/Forwarder/MixinAssets.sol b/packages/contracts/src/2.0.0/extensions/Forwarder/MixinAssets.sol
index d6a38aa6e..43efb5ff3 100644
--- a/packages/contracts/src/2.0.0/extensions/Forwarder/MixinAssets.sol
+++ b/packages/contracts/src/2.0.0/extensions/Forwarder/MixinAssets.sol
@@ -31,7 +31,6 @@ contract MixinAssets is
     LibConstants,
     MAssets
 {
-
     using LibBytes for bytes;
 
     bytes4 constant internal ERC20_TRANSFER_SELECTOR = bytes4(keccak256("transfer(address,uint256)"));
diff --git a/packages/contracts/src/2.0.0/extensions/Forwarder/MixinExchangeWrapper.sol b/packages/contracts/src/2.0.0/extensions/Forwarder/MixinExchangeWrapper.sol
index 9e816716c..fea9a53c2 100644
--- a/packages/contracts/src/2.0.0/extensions/Forwarder/MixinExchangeWrapper.sol
+++ b/packages/contracts/src/2.0.0/extensions/Forwarder/MixinExchangeWrapper.sol
@@ -34,7 +34,6 @@ contract MixinExchangeWrapper is
     LibConstants,
     MExchangeWrapper
 {
-
     /// @dev Fills the input order.
     ///      Returns false if the transaction would otherwise revert.
     /// @param order Order struct containing order specifications.
@@ -61,7 +60,7 @@ contract MixinExchangeWrapper is
         // Call `fillOrder` and handle any exceptions gracefully
         assembly {
             let success := call(
-                gas,                                // forward all gas, TODO: look into gas consumption of assert/throw
+                gas,                                // forward all gas
                 exchange,                           // call address of Exchange contract
                 0,                                  // transfer 0 wei
                 add(fillOrderCalldata, 32),         // pointer to start of input (skip array length in first 32 bytes)
diff --git a/packages/contracts/src/2.0.0/extensions/Forwarder/MixinForwarderCore.sol b/packages/contracts/src/2.0.0/extensions/Forwarder/MixinForwarderCore.sol
index 14f191879..54487f726 100644
--- a/packages/contracts/src/2.0.0/extensions/Forwarder/MixinForwarderCore.sol
+++ b/packages/contracts/src/2.0.0/extensions/Forwarder/MixinForwarderCore.sol
@@ -39,7 +39,6 @@ contract MixinForwarderCore is
     MExchangeWrapper,
     IForwarderCore
 {
-
     using LibBytes for bytes;
 
     /// @dev Constructor approves ERC20 proxy to transfer ZRX and WETH on this contract's behalf.
@@ -47,10 +46,12 @@ contract MixinForwarderCore is
         public
     {
         address proxyAddress = EXCHANGE.getAssetProxy(ERC20_DATA_ID);
-        if (proxyAddress != address(0)) {
-            ETHER_TOKEN.approve(proxyAddress, MAX_UINT);
-            ZRX_TOKEN.approve(proxyAddress, MAX_UINT);
-        }
+        require(
+            proxyAddress != address(0),
+            "UNREGISTERED_ASSET_PROXY"
+        );
+        ETHER_TOKEN.approve(proxyAddress, MAX_UINT);
+        ZRX_TOKEN.approve(proxyAddress, MAX_UINT);
     }
 
     /// @dev Purchases as much of orders' makerAssets as possible by selling up to 95% of transaction's ETH value.
diff --git a/packages/contracts/src/2.0.0/extensions/Forwarder/MixinWeth.sol b/packages/contracts/src/2.0.0/extensions/Forwarder/MixinWeth.sol
index 5863b522d..d2814a49b 100644
--- a/packages/contracts/src/2.0.0/extensions/Forwarder/MixinWeth.sol
+++ b/packages/contracts/src/2.0.0/extensions/Forwarder/MixinWeth.sol
@@ -28,7 +28,6 @@ contract MixinWeth is
     LibConstants,
     MWeth
 {
-
     /// @dev Default payabale function, this allows us to withdraw WETH
     function ()
         public
diff --git a/packages/contracts/src/2.0.0/extensions/Forwarder/mixins/MAssets.sol b/packages/contracts/src/2.0.0/extensions/Forwarder/mixins/MAssets.sol
index 83636432a..9e7f80d97 100644
--- a/packages/contracts/src/2.0.0/extensions/Forwarder/mixins/MAssets.sol
+++ b/packages/contracts/src/2.0.0/extensions/Forwarder/mixins/MAssets.sol
@@ -24,7 +24,6 @@ import "../interfaces/IAssets.sol";
 contract MAssets is
     IAssets
 {
-
     /// @dev Transfers given amount of asset to sender.
     /// @param assetData Byte array encoded for the respective asset proxy.
     /// @param amount Amount of asset to transfer to sender.
diff --git a/packages/contracts/src/2.0.0/extensions/OrderValidator/OrderValidator.sol b/packages/contracts/src/2.0.0/extensions/OrderValidator/OrderValidator.sol
index a18345245..8bfde3847 100644
--- a/packages/contracts/src/2.0.0/extensions/OrderValidator/OrderValidator.sol
+++ b/packages/contracts/src/2.0.0/extensions/OrderValidator/OrderValidator.sol
@@ -28,11 +28,11 @@ import "../../utils/LibBytes/LibBytes.sol";
 
 contract OrderValidator {
 
+    using LibBytes for bytes;
+
     bytes4 constant internal ERC20_DATA_ID = bytes4(keccak256("ERC20Token(address)"));
     bytes4 constant internal ERC721_DATA_ID = bytes4(keccak256("ERC721Token(address,uint256)"));
 
-    using LibBytes for bytes;
-
     struct TraderInfo {
         uint256 makerBalance;       // Maker's balance of makerAsset
         uint256 makerAllowance;     // Maker's allowance to corresponding AssetProxy
diff --git a/packages/contracts/src/2.0.0/multisig/MultiSigWallet.sol b/packages/contracts/src/2.0.0/multisig/MultiSigWallet.sol
index eb54fe047..516e7391c 100644
--- a/packages/contracts/src/2.0.0/multisig/MultiSigWallet.sol
+++ b/packages/contracts/src/2.0.0/multisig/MultiSigWallet.sol
@@ -1,13 +1,14 @@
 // solhint-disable
-pragma solidity ^0.4.10;
+pragma solidity ^0.4.15;
 
 
 /// @title Multisignature wallet - Allows multiple parties to agree on transactions before execution.
 /// @author Stefan George - <stefan.george@consensys.net>
 contract MultiSigWallet {
 
-    uint constant public MAX_OWNER_COUNT = 50;
-
+    /*
+     *  Events
+     */
     event Confirmation(address indexed sender, uint indexed transactionId);
     event Revocation(address indexed sender, uint indexed transactionId);
     event Submission(uint indexed transactionId);
@@ -18,6 +19,14 @@ contract MultiSigWallet {
     event OwnerRemoval(address indexed owner);
     event RequirementChange(uint required);
 
+    /*
+     *  Constants
+     */
+    uint constant public MAX_OWNER_COUNT = 50;
+
+    /*
+     *  Storage
+     */
     mapping (uint => Transaction) public transactions;
     mapping (uint => mapping (address => bool)) public confirmations;
     mapping (address => bool) public isOwner;
@@ -32,60 +41,54 @@ contract MultiSigWallet {
         bool executed;
     }
 
+    /*
+     *  Modifiers
+     */
     modifier onlyWallet() {
-        if (msg.sender != address(this))
-            throw;
+        require(msg.sender == address(this));
         _;
     }
 
     modifier ownerDoesNotExist(address owner) {
-        if (isOwner[owner])
-            throw;
+        require(!isOwner[owner]);
         _;
     }
 
     modifier ownerExists(address owner) {
-        if (!isOwner[owner])
-            throw;
+        require(isOwner[owner]);
         _;
     }
 
     modifier transactionExists(uint transactionId) {
-        if (transactions[transactionId].destination == 0)
-            throw;
+        require(transactions[transactionId].destination != 0);
         _;
     }
 
     modifier confirmed(uint transactionId, address owner) {
-        if (!confirmations[transactionId][owner])
-            throw;
+        require(confirmations[transactionId][owner]);
         _;
     }
 
     modifier notConfirmed(uint transactionId, address owner) {
-        if (confirmations[transactionId][owner])
-            throw;
+        require(!confirmations[transactionId][owner]);
         _;
     }
 
     modifier notExecuted(uint transactionId) {
-        if (transactions[transactionId].executed)
-            throw;
+        require(!transactions[transactionId].executed);
         _;
     }
 
     modifier notNull(address _address) {
-        if (_address == 0)
-            throw;
+        require(_address != 0);
         _;
     }
 
     modifier validRequirement(uint ownerCount, uint _required) {
-        if (   ownerCount > MAX_OWNER_COUNT
-            || _required > ownerCount
-            || _required == 0
-            || ownerCount == 0)
-            throw;
+        require(ownerCount <= MAX_OWNER_COUNT
+            && _required <= ownerCount
+            && _required != 0
+            && ownerCount != 0);
         _;
     }
 
@@ -108,8 +111,7 @@ contract MultiSigWallet {
         validRequirement(_owners.length, _required)
     {
         for (uint i=0; i<_owners.length; i++) {
-            if (isOwner[_owners[i]] || _owners[i] == 0)
-                throw;
+            require(!isOwner[_owners[i]] && _owners[i] != 0);
             isOwner[_owners[i]] = true;
         }
         owners = _owners;
@@ -151,7 +153,7 @@ contract MultiSigWallet {
 
     /// @dev Allows to replace an owner with a new owner. Transaction has to be sent by wallet.
     /// @param owner Address of owner to be replaced.
-    /// @param owner Address of new owner.
+    /// @param newOwner Address of new owner.
     function replaceOwner(address owner, address newOwner)
         public
         onlyWallet
@@ -222,20 +224,44 @@ contract MultiSigWallet {
     /// @param transactionId Transaction ID.
     function executeTransaction(uint transactionId)
         public
+        ownerExists(msg.sender)
+        confirmed(transactionId, msg.sender)
         notExecuted(transactionId)
     {
         if (isConfirmed(transactionId)) {
-            Transaction tx = transactions[transactionId];
-            tx.executed = true;
-            if (tx.destination.call.value(tx.value)(tx.data))
+            Transaction storage txn = transactions[transactionId];
+            txn.executed = true;
+            if (external_call(txn.destination, txn.value, txn.data.length, txn.data))
                 Execution(transactionId);
             else {
                 ExecutionFailure(transactionId);
-                tx.executed = false;
+                txn.executed = false;
             }
         }
     }
 
+    // call has been separated into its own function in order to take advantage
+    // of the Solidity's code generator to produce a loop that copies tx.data into memory.
+    function external_call(address destination, uint value, uint dataLength, bytes data) internal returns (bool) {
+        bool result;
+        assembly {
+            let x := mload(0x40)   // "Allocate" memory for output (0x40 is where "free memory" pointer is stored by convention)
+            let d := add(data, 32) // First 32 bytes are the padded length of data, so exclude that
+            result := call(
+                sub(gas, 34710),   // 34710 is the value that solidity is currently emitting
+                                   // It includes callGas (700) + callVeryLow (3, to pay for SUB) + callValueTransferGas (9000) +
+                                   // callNewAccountGas (25000, in case the destination address does not exist and needs creating)
+                destination,
+                value,
+                d,
+                dataLength,        // Size of the input (in bytes) - this is what fixes the padding problem
+                x,
+                0                  // Output is ignored, therefore the output size is zero
+            )
+        }
+        return result;
+    }
+
     /// @dev Returns the confirmation status of a transaction.
     /// @param transactionId Transaction ID.
     /// @return Confirmation status.
@@ -364,4 +390,4 @@ contract MultiSigWallet {
         for (i=from; i<to; i++)
             _transactionIds[i - from] = transactionIdsTemp[i];
     }
-}
+}
\ No newline at end of file
diff --git a/packages/contracts/src/2.0.0/multisig/MultiSigWalletWithTimeLock.sol b/packages/contracts/src/2.0.0/multisig/MultiSigWalletWithTimeLock.sol
index 8c5e6e1e6..9513d3b30 100644
--- a/packages/contracts/src/2.0.0/multisig/MultiSigWalletWithTimeLock.sol
+++ b/packages/contracts/src/2.0.0/multisig/MultiSigWalletWithTimeLock.sol
@@ -16,47 +16,57 @@
 
 */
 
-// solhint-disable
-pragma solidity ^0.4.10;
+pragma solidity 0.4.24;
 
 import "./MultiSigWallet.sol";
 
 
 /// @title Multisignature wallet with time lock- Allows multiple parties to execute a transaction after a time lock has passed.
 /// @author Amir Bandeali - <amir@0xProject.com>
-contract MultiSigWalletWithTimeLock is MultiSigWallet {
-
-    event ConfirmationTimeSet(uint indexed transactionId, uint confirmationTime);
-    event TimeLockChange(uint secondsTimeLocked);
-
-    uint public secondsTimeLocked;
-
-    mapping (uint => uint) public confirmationTimes;
-
-    modifier notFullyConfirmed(uint transactionId) {
-        require(!isConfirmed(transactionId));
+// solhint-disable not-rely-on-time
+contract MultiSigWalletWithTimeLock is
+    MultiSigWallet
+{
+    event ConfirmationTimeSet(uint256 indexed transactionId, uint256 confirmationTime);
+    event TimeLockChange(uint256 secondsTimeLocked);
+
+    uint256 public secondsTimeLocked;
+
+    mapping (uint256 => uint256) public confirmationTimes;
+
+    modifier notFullyConfirmed(uint256 transactionId) {
+        require(
+            !isConfirmed(transactionId),
+            "TX_FULLY_CONFIRMED"
+        );
         _;
     }
 
-    modifier fullyConfirmed(uint transactionId) {
-        require(isConfirmed(transactionId));
+    modifier fullyConfirmed(uint256 transactionId) {
+        require(
+            isConfirmed(transactionId),
+            "TX_NOT_FULLY_CONFIRMED"
+        );
         _;
     }
 
-    modifier pastTimeLock(uint transactionId) {
-        require(block.timestamp >= confirmationTimes[transactionId] + secondsTimeLocked);
+    modifier pastTimeLock(uint256 transactionId) {
+        require(
+            block.timestamp >= confirmationTimes[transactionId] + secondsTimeLocked,
+            "TIME_LOCK_INCOMPLETE"
+        );
         _;
     }
 
-    /*
-     * Public functions
-     */
-
     /// @dev Contract constructor sets initial owners, required number of confirmations, and time lock.
     /// @param _owners List of initial owners.
     /// @param _required Number of required confirmations.
     /// @param _secondsTimeLocked Duration needed after a transaction is confirmed and before it becomes executable, in seconds.
-    function MultiSigWalletWithTimeLock(address[] _owners, uint _required, uint _secondsTimeLocked)
+    constructor (
+        address[] _owners,
+        uint256 _required,
+        uint256 _secondsTimeLocked
+    )
         public
         MultiSigWallet(_owners, _required)
     {
@@ -65,17 +75,17 @@ contract MultiSigWalletWithTimeLock is MultiSigWallet {
 
     /// @dev Changes the duration of the time lock for transactions.
     /// @param _secondsTimeLocked Duration needed after a transaction is confirmed and before it becomes executable, in seconds.
-    function changeTimeLock(uint _secondsTimeLocked)
+    function changeTimeLock(uint256 _secondsTimeLocked)
         public
         onlyWallet
     {
         secondsTimeLocked = _secondsTimeLocked;
-        TimeLockChange(_secondsTimeLocked);
+        emit TimeLockChange(_secondsTimeLocked);
     }
 
     /// @dev Allows an owner to confirm a transaction.
     /// @param transactionId Transaction ID.
-    function confirmTransaction(uint transactionId)
+    function confirmTransaction(uint256 transactionId)
         public
         ownerExists(msg.sender)
         transactionExists(transactionId)
@@ -83,52 +93,35 @@ contract MultiSigWalletWithTimeLock is MultiSigWallet {
         notFullyConfirmed(transactionId)
     {
         confirmations[transactionId][msg.sender] = true;
-        Confirmation(msg.sender, transactionId);
+        emit Confirmation(msg.sender, transactionId);
         if (isConfirmed(transactionId)) {
             setConfirmationTime(transactionId, block.timestamp);
         }
     }
 
-    /// @dev Allows an owner to revoke a confirmation for a transaction.
-    /// @param transactionId Transaction ID.
-    function revokeConfirmation(uint transactionId)
-        public
-        ownerExists(msg.sender)
-        confirmed(transactionId, msg.sender)
-        notExecuted(transactionId)
-        notFullyConfirmed(transactionId)
-    {
-        confirmations[transactionId][msg.sender] = false;
-        Revocation(msg.sender, transactionId);
-    }
-
     /// @dev Allows anyone to execute a confirmed transaction.
     /// @param transactionId Transaction ID.
-    function executeTransaction(uint transactionId)
+    function executeTransaction(uint256 transactionId)
         public
         notExecuted(transactionId)
         fullyConfirmed(transactionId)
         pastTimeLock(transactionId)
     {
-        Transaction storage tx = transactions[transactionId];
-        tx.executed = true;
-        if (tx.destination.call.value(tx.value)(tx.data))
-            Execution(transactionId);
-        else {
-            ExecutionFailure(transactionId);
-            tx.executed = false;
+        Transaction storage txn = transactions[transactionId];
+        txn.executed = true;
+        if (external_call(txn.destination, txn.value, txn.data.length, txn.data)) {
+            emit Execution(transactionId);
+        } else {
+            emit ExecutionFailure(transactionId);
+            txn.executed = false;
         }
     }
 
-    /*
-     * Internal functions
-     */
-
     /// @dev Sets the time of when a submission first passed.
-    function setConfirmationTime(uint transactionId, uint confirmationTime)
+    function setConfirmationTime(uint256 transactionId, uint256 confirmationTime)
         internal
     {
         confirmationTimes[transactionId] = confirmationTime;
-        ConfirmationTimeSet(transactionId, confirmationTime);
+        emit ConfirmationTimeSet(transactionId, confirmationTime);
     }
 }
diff --git a/packages/contracts/src/2.0.0/protocol/AssetProxy/ERC20Proxy.sol b/packages/contracts/src/2.0.0/protocol/AssetProxy/ERC20Proxy.sol
index 004c3892d..258443bca 100644
--- a/packages/contracts/src/2.0.0/protocol/AssetProxy/ERC20Proxy.sol
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxy/ERC20Proxy.sol
@@ -18,7 +18,6 @@
 
 pragma solidity 0.4.24;
 
-import "../../utils/LibBytes/LibBytes.sol";
 import "./MixinAuthorizable.sol";
 
 
@@ -59,15 +58,64 @@ contract ERC20Proxy is
                     mstore(96, 0)
                     revert(0, 100)
                 }
-                
-                /////// Token contract address ///////
-                // The token address is found as follows:
-                // * It is stored at offset 4 in `assetData` contents.
-                // * This is stored at offset 32 from `assetData`.
-                // * The offset to `assetData` from Params is stored at offset
-                //   4 in calldata.
-                // * The offset of Params in calldata is 4.
-                // So we read location 4 and add 32 + 4 + 4 to it.
+
+                // `transferFrom`.
+                // The function is marked `external`, so no abi decodeding is done for
+                // us. Instead, we expect the `calldata` memory to contain the
+                // following:
+                //
+                // | Area     | Offset | Length  | Contents                            |
+                // |----------|--------|---------|-------------------------------------|
+                // | Header   | 0      | 4       | function selector                   |
+                // | Params   |        | 4 * 32  | function parameters:                |
+                // |          | 4      |         |   1. offset to assetData (*)        |
+                // |          | 36     |         |   2. from                           |
+                // |          | 68     |         |   3. to                             |
+                // |          | 100    |         |   4. amount                         |
+                // | Data     |        |         | assetData:                          |
+                // |          | 132    | 32      | assetData Length                    |
+                // |          | 164    | **      | assetData Contents                  |
+                //
+                // (*): offset is computed from start of function parameters, so offset
+                //      by an additional 4 bytes in the calldata.
+                //
+                // (**): see table below to compute length of assetData Contents
+                //
+                // WARNING: The ABIv2 specification allows additional padding between
+                //          the Params and Data section. This will result in a larger
+                //          offset to assetData.
+
+                // Asset data itself is encoded as follows:
+                //
+                // | Area     | Offset | Length  | Contents                            |
+                // |----------|--------|---------|-------------------------------------|
+                // | Header   | 0      | 4       | function selector                   |
+                // | Params   |        | 1 * 32  | function parameters:                |
+                // |          | 4      | 12 + 20 |   1. token address                  |
+
+                // We construct calldata for the `token.transferFrom` ABI.
+                // The layout of this calldata is in the table below.
+                //
+                // | Area     | Offset | Length  | Contents                            |
+                // |----------|--------|---------|-------------------------------------|
+                // | Header   | 0      | 4       | function selector                   |
+                // | Params   |        | 3 * 32  | function parameters:                |
+                // |          | 4      |         |   1. from                           |
+                // |          | 36     |         |   2. to                             |
+                // |          | 68     |         |   3. amount                         |
+
+                /////// Read token address from calldata ///////
+                // * The token address is stored in `assetData`.
+                //
+                // * The "offset to assetData" is stored at offset 4 in the calldata (table 1).
+                //   [assetDataOffsetFromParams = calldataload(4)]
+                //
+                // * Notes that the "offset to assetData" is relative to the "Params" area of calldata;
+                //   add 4 bytes to account for the length of the "Header" area (table 1).
+                //   [assetDataOffsetFromHeader = assetDataOffsetFromParams + 4]
+                //
+                // * The "token address" is offset 32+4=36 bytes into "assetData" (tables 1 & 2).
+                //   [tokenOffset = assetDataOffsetFromHeader + 36 = calldataload(4) + 4 + 36]
                 let token := calldataload(add(calldataload(4), 40))
                 
                 /////// Setup Header Area ///////
diff --git a/packages/contracts/src/2.0.0/protocol/AssetProxy/ERC721Proxy.sol b/packages/contracts/src/2.0.0/protocol/AssetProxy/ERC721Proxy.sol
index 9d0bc0f74..65b664b8b 100644
--- a/packages/contracts/src/2.0.0/protocol/AssetProxy/ERC721Proxy.sol
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxy/ERC721Proxy.sol
@@ -18,7 +18,6 @@
 
 pragma solidity 0.4.24;
 
-import "../../utils/LibBytes/LibBytes.sol";
 import "./MixinAuthorizable.sol";
 
 
@@ -80,6 +79,8 @@ contract ERC721Proxy is
                 // (*): offset is computed from start of function parameters, so offset
                 //      by an additional 4 bytes in the calldata.
                 //
+                // (**): see table below to compute length of assetData Contents
+                //
                 // WARNING: The ABIv2 specification allows additional padding between
                 //          the Params and Data section. This will result in a larger
                 //          offset to assetData.
diff --git a/packages/contracts/src/2.0.0/protocol/AssetProxy/MixinAuthorizable.sol b/packages/contracts/src/2.0.0/protocol/AssetProxy/MixinAuthorizable.sol
index ff4660a31..fe9bbf848 100644
--- a/packages/contracts/src/2.0.0/protocol/AssetProxy/MixinAuthorizable.sol
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxy/MixinAuthorizable.sol
@@ -26,7 +26,6 @@ contract MixinAuthorizable is
     Ownable,
     MAuthorizable
 {
-
     /// @dev Only authorized addresses can invoke functions with this modifier.
     modifier onlyAuthorized {
         require(
diff --git a/packages/contracts/src/2.0.0/protocol/AssetProxy/interfaces/IAssetProxy.sol b/packages/contracts/src/2.0.0/protocol/AssetProxy/interfaces/IAssetProxy.sol
index 3651dd694..b25d2d75a 100644
--- a/packages/contracts/src/2.0.0/protocol/AssetProxy/interfaces/IAssetProxy.sol
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxy/interfaces/IAssetProxy.sol
@@ -24,7 +24,6 @@ import "./IAuthorizable.sol";
 contract IAssetProxy is
     IAuthorizable
 {
-
     /// @dev Transfers assets. Either succeeds or throws.
     /// @param assetData Byte array encoded for the respective asset proxy.
     /// @param from Address to transfer asset from.
diff --git a/packages/contracts/src/2.0.0/protocol/AssetProxy/interfaces/IAuthorizable.sol b/packages/contracts/src/2.0.0/protocol/AssetProxy/interfaces/IAuthorizable.sol
index 8fac43a47..ba1d4aa77 100644
--- a/packages/contracts/src/2.0.0/protocol/AssetProxy/interfaces/IAuthorizable.sol
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxy/interfaces/IAuthorizable.sol
@@ -24,7 +24,6 @@ import "../../../utils/Ownable/IOwnable.sol";
 contract IAuthorizable is
     IOwnable
 {
-
     /// @dev Authorizes an address.
     /// @param target Address to authorize.
     function addAuthorizedAddress(address target)
diff --git a/packages/contracts/src/2.0.0/protocol/AssetProxy/mixins/MAuthorizable.sol b/packages/contracts/src/2.0.0/protocol/AssetProxy/mixins/MAuthorizable.sol
index 8afc8c8d8..d63fb7f6d 100644
--- a/packages/contracts/src/2.0.0/protocol/AssetProxy/mixins/MAuthorizable.sol
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxy/mixins/MAuthorizable.sol
@@ -24,7 +24,6 @@ import "../interfaces/IAuthorizable.sol";
 contract MAuthorizable is
     IAuthorizable
 {
-
     // Event logged when a new address is authorized.
     event AuthorizedAddressAdded(
         address indexed target,
diff --git a/packages/contracts/src/2.0.0/protocol/AssetProxyOwner/AssetProxyOwner.sol b/packages/contracts/src/2.0.0/protocol/AssetProxyOwner/AssetProxyOwner.sol
index 8b7333646..edb788fab 100644
--- a/packages/contracts/src/2.0.0/protocol/AssetProxyOwner/AssetProxyOwner.sol
+++ b/packages/contracts/src/2.0.0/protocol/AssetProxyOwner/AssetProxyOwner.sol
@@ -16,14 +16,16 @@
 
 */
 
-pragma solidity 0.4.10;
+pragma solidity 0.4.24;
 
 import "../../multisig/MultiSigWalletWithTimeLock.sol";
+import "../../utils/LibBytes/LibBytes.sol";
 
 
 contract AssetProxyOwner is
     MultiSigWalletWithTimeLock
 {
+    using LibBytes for bytes;
 
     event AssetProxyRegistration(address assetProxyContract, bool isRegistered);
 
@@ -36,9 +38,15 @@ contract AssetProxyOwner is
     /// @dev Function will revert if the transaction does not call `removeAuthorizedAddressAtIndex`
     ///      on an approved AssetProxy contract.
     modifier validRemoveAuthorizedAddressAtIndexTx(uint256 transactionId) {
-        Transaction storage tx = transactions[transactionId];
-        require(isAssetProxyRegistered[tx.destination]);
-        require(readBytes4(tx.data, 0) == REMOVE_AUTHORIZED_ADDRESS_AT_INDEX_SELECTOR);
+        Transaction storage txn = transactions[transactionId];
+        require(
+            isAssetProxyRegistered[txn.destination],
+            "UNREGISTERED_ASSET_PROXY"
+        );
+        require(
+            txn.data.readBytes4(0) == REMOVE_AUTHORIZED_ADDRESS_AT_INDEX_SELECTOR,
+            "INVALID_FUNCTION_SELECTOR"
+        );
         _;
     }
 
@@ -48,7 +56,7 @@ contract AssetProxyOwner is
     /// @param _assetProxyContracts Array of AssetProxy contract addresses.
     /// @param _required Number of required confirmations.
     /// @param _secondsTimeLocked Duration needed after a transaction is confirmed and before it becomes executable, in seconds.
-    function AssetProxyOwner(
+    constructor (
         address[] memory _owners,
         address[] memory _assetProxyContracts,
         uint256 _required,
@@ -59,7 +67,10 @@ contract AssetProxyOwner is
     {
         for (uint256 i = 0; i < _assetProxyContracts.length; i++) {
             address assetProxy = _assetProxyContracts[i];
-            require(assetProxy != address(0));
+            require(
+                assetProxy != address(0),
+                "INVALID_ASSET_PROXY"
+            );
             isAssetProxyRegistered[assetProxy] = true;
         }
     }
@@ -74,7 +85,7 @@ contract AssetProxyOwner is
         notNull(assetProxyContract)
     {
         isAssetProxyRegistered[assetProxyContract] = isRegistered;
-        AssetProxyRegistration(assetProxyContract, isRegistered);
+        emit AssetProxyRegistration(assetProxyContract, isRegistered);
     }
 
     /// @dev Allows execution of `removeAuthorizedAddressAtIndex` without time lock.
@@ -85,35 +96,13 @@ contract AssetProxyOwner is
         fullyConfirmed(transactionId)
         validRemoveAuthorizedAddressAtIndexTx(transactionId)
     {
-        Transaction storage tx = transactions[transactionId];
-        tx.executed = true;
-        // solhint-disable-next-line avoid-call-value
-        if (tx.destination.call.value(tx.value)(tx.data))
-            Execution(transactionId);
-        else {
-            ExecutionFailure(transactionId);
-            tx.executed = false;
+        Transaction storage txn = transactions[transactionId];
+        txn.executed = true;
+        if (external_call(txn.destination, txn.value, txn.data.length, txn.data)) {
+            emit Execution(transactionId);
+        } else {
+            emit ExecutionFailure(transactionId);
+            txn.executed = false;
         }
     }
-
-    /// @dev Reads an unpadded bytes4 value from a position in a byte array.
-    /// @param b Byte array containing a bytes4 value.
-    /// @param index Index in byte array of bytes4 value.
-    /// @return bytes4 value from byte array.
-    function readBytes4(
-        bytes memory b,
-        uint256 index
-    )
-        internal
-        returns (bytes4 result)
-    {
-        require(b.length >= index + 4);
-        assembly {
-            result := mload(add(b, 32))
-            // Solidity does not require us to clean the trailing bytes.
-            // We do it anyway
-            result := and(result, 0xFFFFFFFF00000000000000000000000000000000000000000000000000000000)
-        }
-        return result;
-    }
 }
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/Exchange.sol b/packages/contracts/src/2.0.0/protocol/Exchange/Exchange.sol
index 7507d3da1..ead36009f 100644
--- a/packages/contracts/src/2.0.0/protocol/Exchange/Exchange.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/Exchange.sol
@@ -37,7 +37,6 @@ contract Exchange is
     MixinAssetProxyDispatcher,
     MixinWrapperFunctions
 {
-
     string constant public VERSION = "2.0.1-alpha";
 
     // Mixins are instantiated in the order they are inherited
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/MixinAssetProxyDispatcher.sol b/packages/contracts/src/2.0.0/protocol/Exchange/MixinAssetProxyDispatcher.sol
index 80475e6e3..87b09b6b3 100644
--- a/packages/contracts/src/2.0.0/protocol/Exchange/MixinAssetProxyDispatcher.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/MixinAssetProxyDispatcher.sol
@@ -19,7 +19,6 @@
 pragma solidity 0.4.24;
 
 import "../../utils/Ownable/Ownable.sol";
-import "../../utils/LibBytes/LibBytes.sol";
 import "./mixins/MAssetProxyDispatcher.sol";
 import "../AssetProxy/interfaces/IAssetProxy.sol";
 
@@ -28,8 +27,6 @@ contract MixinAssetProxyDispatcher is
     Ownable,
     MAssetProxyDispatcher
 {
-    using LibBytes for bytes;
-    
     // Mapping from Asset Proxy Id's to their respective Asset Proxy
     mapping (bytes4 => IAssetProxy) public assetProxies;
 
@@ -90,7 +87,7 @@ contract MixinAssetProxyDispatcher is
                 "LENGTH_GREATER_THAN_3_REQUIRED"
             );
             
-            // Lookup assetProxy
+            // Lookup assetProxy. We do not use `LibBytes.readBytes4` for gas efficiency reasons.
             bytes4 assetProxyId;
             assembly {
                 assetProxyId := and(mload(
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/MixinExchangeCore.sol b/packages/contracts/src/2.0.0/protocol/Exchange/MixinExchangeCore.sol
index be163ec97..736dcd0b1 100644
--- a/packages/contracts/src/2.0.0/protocol/Exchange/MixinExchangeCore.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/MixinExchangeCore.sol
@@ -75,7 +75,11 @@ contract MixinExchangeCore is
 
         // Update orderEpoch
         orderEpoch[makerAddress][senderAddress] = newOrderEpoch;
-        emit CancelUpTo(makerAddress, senderAddress, newOrderEpoch);
+        emit CancelUpTo(
+            makerAddress,
+            senderAddress,
+            newOrderEpoch
+        );
     }
 
     /// @dev Fills the input order.
@@ -107,14 +111,7 @@ contract MixinExchangeCore is
         public
         nonReentrant
     {
-        // Fetch current order status
-        OrderInfo memory orderInfo = getOrderInfo(order);
-
-        // Validate context
-        assertValidCancel(order, orderInfo);
-
-        // Perform cancel
-        updateCancelledState(order, orderInfo.orderHash);
+        cancelOrderInternal(order);
     }
 
     /// @dev Gets information about an order: status, hash, and amount filled.
@@ -231,11 +228,31 @@ contract MixinExchangeCore is
         );
     
         // Settle order
-        settleOrder(order, takerAddress, fillResults);
+        settleOrder(
+            order,
+            takerAddress,
+            fillResults
+        );
 
         return fillResults;
     }
 
+    /// @dev After calling, the order can not be filled anymore.
+    ///      Throws if order is invalid or sender does not have permission to cancel.
+    /// @param order Order to cancel. Order must be OrderStatus.FILLABLE.
+    function cancelOrderInternal(Order memory order)
+        internal
+    {
+        // Fetch current order status
+        OrderInfo memory orderInfo = getOrderInfo(order);
+
+        // Validate context
+        assertValidCancel(order, orderInfo);
+
+        // Perform cancel
+        updateCancelledState(order, orderInfo.orderHash);
+    }
+
     /// @dev Updates state with results of a fill order.
     /// @param order that was filled.
     /// @param takerAddress Address of taker who filled the order.
@@ -404,16 +421,6 @@ contract MixinExchangeCore is
             safeMul(order.makerAssetAmount, takerAssetFilledAmount),
             "INVALID_FILL_PRICE"
         );
-        
-        // Validate fill order rounding
-        require(
-            !isRoundingErrorFloor(
-                takerAssetFilledAmount,
-                order.takerAssetAmount,
-                order.makerAssetAmount
-            ),
-            "ROUNDING_ERROR"
-        );
     }
 
     /// @dev Validates context for cancelOrder. Succeeds or throws.
@@ -463,17 +470,17 @@ contract MixinExchangeCore is
     {
         // Compute proportional transfer amounts
         fillResults.takerAssetFilledAmount = takerAssetFilledAmount;
-        fillResults.makerAssetFilledAmount = getPartialAmountFloor(
+        fillResults.makerAssetFilledAmount = safeGetPartialAmountFloor(
             takerAssetFilledAmount,
             order.takerAssetAmount,
             order.makerAssetAmount
         );
-        fillResults.makerFeePaid = getPartialAmountFloor(
-            takerAssetFilledAmount,
-            order.takerAssetAmount,
+        fillResults.makerFeePaid = safeGetPartialAmountFloor(
+            fillResults.makerAssetFilledAmount,
+            order.makerAssetAmount,
             order.makerFee
         );
-        fillResults.takerFeePaid = getPartialAmountFloor(
+        fillResults.takerFeePaid = safeGetPartialAmountFloor(
             takerAssetFilledAmount,
             order.takerAssetAmount,
             order.takerFee
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/MixinMatchOrders.sol b/packages/contracts/src/2.0.0/protocol/Exchange/MixinMatchOrders.sol
index 075a610b5..b4f6bdb26 100644
--- a/packages/contracts/src/2.0.0/protocol/Exchange/MixinMatchOrders.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/MixinMatchOrders.sol
@@ -177,13 +177,13 @@ contract MixinMatchOrders is
     {
         // Derive maker asset amounts for left & right orders, given store taker assert amounts
         uint256 leftTakerAssetAmountRemaining = safeSub(leftOrder.takerAssetAmount, leftOrderTakerAssetFilledAmount);
-        uint256 leftMakerAssetAmountRemaining = getPartialAmountFloor(
+        uint256 leftMakerAssetAmountRemaining = safeGetPartialAmountFloor(
             leftOrder.makerAssetAmount,
             leftOrder.takerAssetAmount,
             leftTakerAssetAmountRemaining
         );
         uint256 rightTakerAssetAmountRemaining = safeSub(rightOrder.takerAssetAmount, rightOrderTakerAssetFilledAmount);
-        uint256 rightMakerAssetAmountRemaining = getPartialAmountFloor(
+        uint256 rightMakerAssetAmountRemaining = safeGetPartialAmountFloor(
             rightOrder.makerAssetAmount,
             rightOrder.takerAssetAmount,
             rightTakerAssetAmountRemaining
@@ -205,7 +205,7 @@ contract MixinMatchOrders is
             matchedFillResults.left.takerAssetFilledAmount = matchedFillResults.right.makerAssetFilledAmount;
             // Round down to ensure the maker's exchange rate does not exceed the price specified by the order. 
             // We favor the maker when the exchange rate must be rounded.
-            matchedFillResults.left.makerAssetFilledAmount = getPartialAmountFloor(
+            matchedFillResults.left.makerAssetFilledAmount = safeGetPartialAmountFloor(
                 leftOrder.makerAssetAmount,
                 leftOrder.takerAssetAmount,
                 matchedFillResults.left.takerAssetFilledAmount
@@ -217,7 +217,7 @@ contract MixinMatchOrders is
             matchedFillResults.right.makerAssetFilledAmount = matchedFillResults.left.takerAssetFilledAmount;
             // Round up to ensure the maker's exchange rate does not exceed the price specified by the order.
             // We favor the maker when the exchange rate must be rounded.
-            matchedFillResults.right.takerAssetFilledAmount = getPartialAmountCeil(
+            matchedFillResults.right.takerAssetFilledAmount = safeGetPartialAmountCeil(
                 rightOrder.takerAssetAmount,
                 rightOrder.makerAssetAmount,
                 matchedFillResults.right.makerAssetFilledAmount
@@ -231,24 +231,24 @@ contract MixinMatchOrders is
         );
 
         // Compute fees for left order
-        matchedFillResults.left.makerFeePaid = getPartialAmountFloor(
+        matchedFillResults.left.makerFeePaid = safeGetPartialAmountFloor(
             matchedFillResults.left.makerAssetFilledAmount,
             leftOrder.makerAssetAmount,
             leftOrder.makerFee
         );
-        matchedFillResults.left.takerFeePaid = getPartialAmountFloor(
+        matchedFillResults.left.takerFeePaid = safeGetPartialAmountFloor(
             matchedFillResults.left.takerAssetFilledAmount,
             leftOrder.takerAssetAmount,
             leftOrder.takerFee
         );
 
         // Compute fees for right order
-        matchedFillResults.right.makerFeePaid = getPartialAmountFloor(
+        matchedFillResults.right.makerFeePaid = safeGetPartialAmountFloor(
             matchedFillResults.right.makerAssetFilledAmount,
             rightOrder.makerAssetAmount,
             rightOrder.makerFee
         );
-        matchedFillResults.right.takerFeePaid = getPartialAmountFloor(
+        matchedFillResults.right.takerFeePaid = safeGetPartialAmountFloor(
             matchedFillResults.right.takerAssetFilledAmount,
             rightOrder.takerAssetAmount,
             rightOrder.takerFee
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/MixinSignatureValidator.sol b/packages/contracts/src/2.0.0/protocol/Exchange/MixinSignatureValidator.sol
index 4eb6a2fa6..176e28351 100644
--- a/packages/contracts/src/2.0.0/protocol/Exchange/MixinSignatureValidator.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/MixinSignatureValidator.sol
@@ -251,7 +251,7 @@ contract MixinSignatureValidator is
                 walletAddress,    // address of Wallet contract
                 cdStart,          // pointer to start of input
                 mload(calldata),  // length of input
-                cdStart,          // write input over output
+                cdStart,          // write output over input
                 32                // output size is 32 bytes
             )
 
@@ -301,7 +301,7 @@ contract MixinSignatureValidator is
                 validatorAddress,  // address of Validator contract
                 cdStart,           // pointer to start of input
                 mload(calldata),   // length of input
-                cdStart,           // write input over output
+                cdStart,           // write output over input
                 32                 // output size is 32 bytes
             )
 
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/MixinTransactions.sol b/packages/contracts/src/2.0.0/protocol/Exchange/MixinTransactions.sol
index 4a59b6c0f..3a76ca202 100644
--- a/packages/contracts/src/2.0.0/protocol/Exchange/MixinTransactions.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/MixinTransactions.sol
@@ -28,7 +28,6 @@ contract MixinTransactions is
     MSignatureValidator,
     MTransactions
 {
-
     // Mapping of transaction hash => executed
     // This prevents transactions from being executed more than once.
     mapping (bytes32 => bool) public transactions;
@@ -36,15 +35,6 @@ contract MixinTransactions is
     // Address of current transaction signer
     address public currentContextAddress;
 
-    // Hash for the EIP712 ZeroEx Transaction Schema
-    bytes32 constant internal EIP712_ZEROEX_TRANSACTION_SCHEMA_HASH = keccak256(abi.encodePacked(
-        "ZeroExTransaction(",
-        "uint256 salt,",
-        "address signerAddress,",
-        "bytes data",
-        ")"
-    ));
-
     /// @dev Executes an exchange method call in the context of signer.
     /// @param salt Arbitrary number to ensure uniqueness of transaction hash.
     /// @param signerAddress Address of transaction signer.
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/MixinWrapperFunctions.sol b/packages/contracts/src/2.0.0/protocol/Exchange/MixinWrapperFunctions.sol
index a5459a21e..cddff0e5f 100644
--- a/packages/contracts/src/2.0.0/protocol/Exchange/MixinWrapperFunctions.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/MixinWrapperFunctions.sol
@@ -36,7 +36,6 @@ contract MixinWrapperFunctions is
     MExchangeCore,
     MWrapperFunctions
 {
-
     /// @dev Fills the input order. Reverts if exact takerAssetFillAmount not filled.
     /// @param order Order struct containing order specifications.
     /// @param takerAssetFillAmount Desired amount of takerAsset to sell.
@@ -82,7 +81,7 @@ contract MixinWrapperFunctions is
         // Delegate to `fillOrder` and handle any exceptions gracefully
         assembly {
             let success := delegatecall(
-                gas,                                // forward all gas, TODO: look into gas consumption of assert/throw
+                gas,                                // forward all gas
                 address,                            // call address of this contract
                 add(fillOrderCalldata, 32),         // pointer to start of input (skip array length in first 32 bytes)
                 mload(fillOrderCalldata),           // length of input
@@ -377,10 +376,11 @@ contract MixinWrapperFunctions is
     /// @param orders Array of order specifications.
     function batchCancelOrders(LibOrder.Order[] memory orders)
         public
+        nonReentrant
     {
         uint256 ordersLength = orders.length;
         for (uint256 i = 0; i != ordersLength; i++) {
-            cancelOrder(orders[i]);
+            cancelOrderInternal(orders[i]);
         }
     }
 
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibEIP712.sol b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibEIP712.sol
index b02f7632e..203edc1fd 100644
--- a/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibEIP712.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibEIP712.sol
@@ -20,6 +20,7 @@ pragma solidity 0.4.24;
 
 
 contract LibEIP712 {
+
     // EIP191 header for EIP712 prefix
     string constant internal EIP191_HEADER = "\x19\x01";
 
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibFillResults.sol b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibFillResults.sol
index 1b4181d94..659ae9a69 100644
--- a/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibFillResults.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibFillResults.sol
@@ -24,7 +24,6 @@ import "../../../utils/SafeMath/SafeMath.sol";
 contract LibFillResults is
     SafeMath
 {
-
     struct FillResults {
         uint256 makerAssetFilledAmount;  // Total amount of makerAsset(s) filled.
         uint256 takerAssetFilledAmount;  // Total amount of takerAsset(s) filled.
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibMath.sol b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibMath.sol
index 0e0fba5d2..c0b85ea10 100644
--- a/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibMath.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibMath.sol
@@ -24,6 +24,83 @@ import "../../../utils/SafeMath/SafeMath.sol";
 contract LibMath is
     SafeMath
 {
+    /// @dev Calculates partial value given a numerator and denominator rounded down.
+    ///      Reverts if rounding error is >= 0.1%
+    /// @param numerator Numerator.
+    /// @param denominator Denominator.
+    /// @param target Value to calculate partial of.
+    /// @return Partial value of target rounded down.
+    function safeGetPartialAmountFloor(
+        uint256 numerator,
+        uint256 denominator,
+        uint256 target
+    )
+        internal
+        pure
+        returns (uint256 partialAmount)
+    {
+        require(
+            denominator > 0,
+            "DIVISION_BY_ZERO"
+        );
+
+        require(
+            !isRoundingErrorFloor(
+                numerator,
+                denominator,
+                target
+            ),
+            "ROUNDING_ERROR"
+        );
+        
+        partialAmount = safeDiv(
+            safeMul(numerator, target),
+            denominator
+        );
+        return partialAmount;
+    }
+
+    /// @dev Calculates partial value given a numerator and denominator rounded down.
+    ///      Reverts if rounding error is >= 0.1%
+    /// @param numerator Numerator.
+    /// @param denominator Denominator.
+    /// @param target Value to calculate partial of.
+    /// @return Partial value of target rounded up.
+    function safeGetPartialAmountCeil(
+        uint256 numerator,
+        uint256 denominator,
+        uint256 target
+    )
+        internal
+        pure
+        returns (uint256 partialAmount)
+    {
+        require(
+            denominator > 0,
+            "DIVISION_BY_ZERO"
+        );
+
+        require(
+            !isRoundingErrorCeil(
+                numerator,
+                denominator,
+                target
+            ),
+            "ROUNDING_ERROR"
+        );
+        
+        // safeDiv computes `floor(a / b)`. We use the identity (a, b integer):
+        //       ceil(a / b) = floor((a + b - 1) / b)
+        // To implement `ceil(a / b)` using safeDiv.
+        partialAmount = safeDiv(
+            safeAdd(
+                safeMul(numerator, target),
+                safeSub(denominator, 1)
+            ),
+            denominator
+        );
+        return partialAmount;
+    }
 
     /// @dev Calculates partial value given a numerator and denominator rounded down.
     /// @param numerator Numerator.
@@ -43,7 +120,7 @@ contract LibMath is
             denominator > 0,
             "DIVISION_BY_ZERO"
         );
-        
+
         partialAmount = safeDiv(
             safeMul(numerator, target),
             denominator
@@ -69,7 +146,7 @@ contract LibMath is
             denominator > 0,
             "DIVISION_BY_ZERO"
         );
-        
+
         // safeDiv computes `floor(a / b)`. We use the identity (a, b integer):
         //       ceil(a / b) = floor((a + b - 1) / b)
         // To implement `ceil(a / b)` using safeDiv.
@@ -128,7 +205,11 @@ contract LibMath is
         //        1000 * remainder  <  numerator * target
         // so we have a rounding error iff:
         //        1000 * remainder  >=  numerator * target
-        uint256 remainder = mulmod(target, numerator, denominator);
+        uint256 remainder = mulmod(
+            target,
+            numerator,
+            denominator
+        );
         isError = safeMul(1000, remainder) >= safeMul(numerator, target);
         return isError;
     }
@@ -160,8 +241,11 @@ contract LibMath is
             return false;
         }
         // Compute remainder as before
-        uint256 remainder = mulmod(target, numerator, denominator);
-        // TODO: safeMod
+        uint256 remainder = mulmod(
+            target,
+            numerator,
+            denominator
+        );
         remainder = safeSub(denominator, remainder) % denominator;
         isError = safeMul(1000, remainder) >= safeMul(numerator, target);
         return isError;
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibOrder.sol b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibOrder.sol
index 68f4f5f1b..0fe7c2161 100644
--- a/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibOrder.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/libs/LibOrder.sol
@@ -24,7 +24,6 @@ import "./LibEIP712.sol";
 contract LibOrder is
     LibEIP712
 {
-
     // Hash for the EIP712 Order Schema
     bytes32 constant internal EIP712_ORDER_SCHEMA_HASH = keccak256(abi.encodePacked(
         "Order(",
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MAssetProxyDispatcher.sol b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MAssetProxyDispatcher.sol
index c6904300a..0ddfca270 100644
--- a/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MAssetProxyDispatcher.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MAssetProxyDispatcher.sol
@@ -24,7 +24,6 @@ import "../interfaces/IAssetProxyDispatcher.sol";
 contract MAssetProxyDispatcher is
     IAssetProxyDispatcher
 {
-
     // Logs registration of new asset proxy
     event AssetProxyRegistered(
         bytes4 id,              // Id of new registered AssetProxy.
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MExchangeCore.sol b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MExchangeCore.sol
index d85913e0f..742499568 100644
--- a/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MExchangeCore.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MExchangeCore.sol
@@ -72,6 +72,11 @@ contract MExchangeCore is
         internal
         returns (LibFillResults.FillResults memory fillResults);
 
+    /// @dev After calling, the order can not be filled anymore.
+    /// @param order Order struct containing order specifications.
+    function cancelOrderInternal(LibOrder.Order memory order)
+        internal;
+
     /// @dev Updates state with results of a fill order.
     /// @param order that was filled.
     /// @param takerAddress Address of taker who filled the order.
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MMatchOrders.sol b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MMatchOrders.sol
index a31ec1585..96fa34bc0 100644
--- a/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MMatchOrders.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MMatchOrders.sol
@@ -26,7 +26,6 @@ import "../interfaces/IMatchOrders.sol";
 contract MMatchOrders is
     IMatchOrders
 {
-
     /// @dev Validates context for matchOrders. Succeeds or throws.
     /// @param leftOrder First order to match.
     /// @param rightOrder Second order to match.
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MTransactions.sol b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MTransactions.sol
index f2b5e4b16..4f61a4945 100644
--- a/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MTransactions.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MTransactions.sol
@@ -23,6 +23,28 @@ import "../interfaces/ITransactions.sol";
 contract MTransactions is
     ITransactions
 {
+    // Hash for the EIP712 ZeroEx Transaction Schema
+    bytes32 constant internal EIP712_ZEROEX_TRANSACTION_SCHEMA_HASH = keccak256(abi.encodePacked(
+        "ZeroExTransaction(",
+        "uint256 salt,",
+        "address signerAddress,",
+        "bytes data",
+        ")"
+    ));
+
+    /// @dev Calculates EIP712 hash of the Transaction.
+    /// @param salt Arbitrary number to ensure uniqueness of transaction hash.
+    /// @param signerAddress Address of transaction signer.
+    /// @param data AbiV2 encoded calldata.
+    /// @return EIP712 hash of the Transaction.
+    function hashZeroExTransaction(
+        uint256 salt,
+        address signerAddress,
+        bytes memory data
+    )
+        internal
+        pure
+        returns (bytes32 result);
 
     /// @dev The current function will be called in the context of this address (either 0x transaction signer or `msg.sender`).
     ///      If calling a fill function, this address will represent the taker.
diff --git a/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MWrapperFunctions.sol b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MWrapperFunctions.sol
index e04d4a429..4adfbde01 100644
--- a/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MWrapperFunctions.sol
+++ b/packages/contracts/src/2.0.0/protocol/Exchange/mixins/MWrapperFunctions.sol
@@ -24,8 +24,9 @@ import "../libs/LibFillResults.sol";
 import "../interfaces/IWrapperFunctions.sol";
 
 
-contract MWrapperFunctions {
-
+contract MWrapperFunctions is 
+    IWrapperFunctions
+{
     /// @dev Fills the input order. Reverts if exact takerAssetFillAmount not filled.
     /// @param order LibOrder.Order struct containing order specifications.
     /// @param takerAssetFillAmount Desired amount of takerAsset to sell.
diff --git a/packages/contracts/src/2.0.0/test/DummyERC20Token/DummyMultipleReturnERC20Token.sol b/packages/contracts/src/2.0.0/test/DummyERC20Token/DummyMultipleReturnERC20Token.sol
new file mode 100644
index 000000000..733d4437e
--- /dev/null
+++ b/packages/contracts/src/2.0.0/test/DummyERC20Token/DummyMultipleReturnERC20Token.sol
@@ -0,0 +1,69 @@
+/*
+
+  Copyright 2018 ZeroEx Intl.
+
+  Licensed under the Apache License, Version 2.0 (the "License");
+  you may not use this file except in compliance with the License.
+  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+  Unless required by applicable law or agreed to in writing, software
+  distributed under the License is distributed on an "AS IS" BASIS,
+  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  See the License for the specific language governing permissions and
+  limitations under the License.
+
+*/
+
+pragma solidity 0.4.24;
+
+import "./DummyERC20Token.sol";
+
+
+// solhint-disable no-empty-blocks
+contract DummyMultipleReturnERC20Token is
+    DummyERC20Token
+{
+    constructor (
+        string _name,
+        string _symbol,
+        uint256 _decimals,
+        uint256 _totalSupply
+    )
+        public
+        DummyERC20Token(
+            _name,
+            _symbol,
+            _decimals,
+            _totalSupply
+        )
+    {}
+
+    /// @dev send `value` token to `to` from `from` on the condition it is approved by `from`
+    /// @param _from The address of the sender
+    /// @param _to The address of the recipient
+    /// @param _value The amount of token to be transferred
+    function transferFrom(
+        address _from,
+        address _to,
+        uint256 _value
+    )
+        external
+        returns (bool)
+    {
+        emit Transfer(
+            _from,
+            _to,
+            _value
+        );
+
+        // HACK: This contract will not compile if we remove `returns (bool)`, so we manually return 64 bytes (equiavalent to true, true)
+        assembly {
+            mstore(0, 1)
+            mstore(32, 1)
+            return(0, 64)
+        }
+    }
+}
+
diff --git a/packages/contracts/src/2.0.0/test/DummyERC20Token/DummyNoReturnERC20Token.sol b/packages/contracts/src/2.0.0/test/DummyERC20Token/DummyNoReturnERC20Token.sol
index 79156d3dd..e16825a16 100644
--- a/packages/contracts/src/2.0.0/test/DummyERC20Token/DummyNoReturnERC20Token.sol
+++ b/packages/contracts/src/2.0.0/test/DummyERC20Token/DummyNoReturnERC20Token.sol
@@ -25,7 +25,6 @@ import "./DummyERC20Token.sol";
 contract DummyNoReturnERC20Token is
     DummyERC20Token
 {
-
     constructor (
         string _name,
         string _symbol,
diff --git a/packages/contracts/src/2.0.0/test/DummyERC721Receiver/DummyERC721Receiver.sol b/packages/contracts/src/2.0.0/test/DummyERC721Receiver/DummyERC721Receiver.sol
index ac95e47bd..6c8371559 100644
--- a/packages/contracts/src/2.0.0/test/DummyERC721Receiver/DummyERC721Receiver.sol
+++ b/packages/contracts/src/2.0.0/test/DummyERC721Receiver/DummyERC721Receiver.sol
@@ -24,7 +24,6 @@ import "../../tokens/ERC721Token/IERC721Receiver.sol";
 contract DummyERC721Receiver is
     IERC721Receiver
 {
-
     // Function selector for ERC721Receiver.onERC721Received
     // 0x150b7a02
     bytes4 constant internal ERC721_RECEIVED = bytes4(keccak256("onERC721Received(address,address,uint256,bytes)"));
diff --git a/packages/contracts/src/2.0.0/test/ReentrantERC20Token/ReentrantERC20Token.sol b/packages/contracts/src/2.0.0/test/ReentrantERC20Token/ReentrantERC20Token.sol
index 8bfdd2e66..99dd47a78 100644
--- a/packages/contracts/src/2.0.0/test/ReentrantERC20Token/ReentrantERC20Token.sol
+++ b/packages/contracts/src/2.0.0/test/ReentrantERC20Token/ReentrantERC20Token.sol
@@ -25,10 +25,10 @@ import "../../protocol/Exchange/interfaces/IExchange.sol";
 import "../../protocol/Exchange/libs/LibOrder.sol";
 
 
+// solhint-disable no-unused-vars
 contract ReentrantERC20Token is
     ERC20Token
 {
-
     using LibBytes for bytes;
 
     // solhint-disable-next-line var-name-mixedcase
@@ -50,6 +50,7 @@ contract ReentrantERC20Token is
         MARKET_SELL_ORDERS,
         MATCH_ORDERS,
         CANCEL_ORDER,
+        BATCH_CANCEL_ORDERS,
         CANCEL_ORDERS_UP_TO,
         SET_SIGNATURE_VALIDATOR_APPROVAL
     }
@@ -149,6 +150,11 @@ contract ReentrantERC20Token is
                 EXCHANGE.cancelOrder.selector,
                 order
             );
+        } else if (currentFunctionId == uint8(ExchangeFunction.BATCH_CANCEL_ORDERS)) {
+            calldata = abi.encodeWithSelector(
+                EXCHANGE.batchCancelOrders.selector,
+                orders
+            );
         } else if (currentFunctionId == uint8(ExchangeFunction.CANCEL_ORDERS_UP_TO)) {
             calldata = abi.encodeWithSelector(
                 EXCHANGE.cancelOrdersUpTo.selector,
diff --git a/packages/contracts/src/2.0.0/test/TestAssetProxyOwner/TestAssetProxyOwner.sol b/packages/contracts/src/2.0.0/test/TestAssetProxyOwner/TestAssetProxyOwner.sol
index 75e782d43..52c66cb56 100644
--- a/packages/contracts/src/2.0.0/test/TestAssetProxyOwner/TestAssetProxyOwner.sol
+++ b/packages/contracts/src/2.0.0/test/TestAssetProxyOwner/TestAssetProxyOwner.sol
@@ -16,7 +16,7 @@
 
 */
 
-pragma solidity 0.4.10;
+pragma solidity 0.4.24;
 
 import "../../protocol/AssetProxyOwner/AssetProxyOwner.sol";
 
@@ -25,8 +25,7 @@ import "../../protocol/AssetProxyOwner/AssetProxyOwner.sol";
 contract TestAssetProxyOwner is
     AssetProxyOwner
 {
-
-    function TestAssetProxyOwner(
+    constructor (
         address[] memory _owners,
         address[] memory _assetProxyContracts,
         uint256 _required,
@@ -38,6 +37,7 @@ contract TestAssetProxyOwner is
     
     function testValidRemoveAuthorizedAddressAtIndexTx(uint256 id)
         public
+        view
         validRemoveAuthorizedAddressAtIndexTx(id)
         returns (bool)
     {
@@ -50,23 +50,9 @@ contract TestAssetProxyOwner is
     /// @return Successful if data is a call to `removeAuthorizedAddressAtIndex`.
     function isFunctionRemoveAuthorizedAddressAtIndex(bytes memory data)
         public
+        pure
         returns (bool)
     {
-        return readBytes4(data, 0) == REMOVE_AUTHORIZED_ADDRESS_AT_INDEX_SELECTOR;
-    }
-
-    /// @dev Reads an unpadded bytes4 value from a position in a byte array.
-    /// @param b Byte array containing a bytes4 value.
-    /// @param index Index in byte array of bytes4 value.
-    /// @return bytes4 value from byte array.
-    function publicReadBytes4(
-        bytes memory b,
-        uint256 index
-    )
-        public
-        returns (bytes4 result)
-    {
-        result = readBytes4(b, index);
-        return result;
+        return data.readBytes4(0) == REMOVE_AUTHORIZED_ADDRESS_AT_INDEX_SELECTOR;
     }
 }
diff --git a/packages/contracts/src/2.0.0/test/TestExchangeInternals/TestExchangeInternals.sol b/packages/contracts/src/2.0.0/test/TestExchangeInternals/TestExchangeInternals.sol
index da9313e02..27187f8f8 100644
--- a/packages/contracts/src/2.0.0/test/TestExchangeInternals/TestExchangeInternals.sol
+++ b/packages/contracts/src/2.0.0/test/TestExchangeInternals/TestExchangeInternals.sol
@@ -63,6 +63,42 @@ contract TestExchangeInternals is
     }
 
     /// @dev Calculates partial value given a numerator and denominator.
+    ///      Reverts if rounding error is >= 0.1%
+    /// @param numerator Numerator.
+    /// @param denominator Denominator.
+    /// @param target Value to calculate partial of.
+    /// @return Partial value of target.
+    function publicSafeGetPartialAmountFloor(
+        uint256 numerator,
+        uint256 denominator,
+        uint256 target
+    )
+        public
+        pure
+        returns (uint256 partialAmount)
+    {
+        return safeGetPartialAmountFloor(numerator, denominator, target);
+    }
+
+    /// @dev Calculates partial value given a numerator and denominator.
+    ///      Reverts if rounding error is >= 0.1%
+    /// @param numerator Numerator.
+    /// @param denominator Denominator.
+    /// @param target Value to calculate partial of.
+    /// @return Partial value of target.
+    function publicSafeGetPartialAmountCeil(
+        uint256 numerator,
+        uint256 denominator,
+        uint256 target
+    )
+        public
+        pure
+        returns (uint256 partialAmount)
+    {
+        return safeGetPartialAmountCeil(numerator, denominator, target);
+    }
+
+    /// @dev Calculates partial value given a numerator and denominator.
     /// @param numerator Numerator.
     /// @param denominator Denominator.
     /// @param target Value to calculate partial of.
diff --git a/packages/contracts/src/2.0.0/test/TestLibs/TestLibs.sol b/packages/contracts/src/2.0.0/test/TestLibs/TestLibs.sol
index c8c58545f..a10f981fc 100644
--- a/packages/contracts/src/2.0.0/test/TestLibs/TestLibs.sol
+++ b/packages/contracts/src/2.0.0/test/TestLibs/TestLibs.sol
@@ -31,7 +31,6 @@ contract TestLibs is
     LibFillResults,
     LibAbiEncoder
 {
-
     function publicAbiEncodeFillOrder(
         Order memory order,
         uint256 takerAssetFillAmount,
diff --git a/packages/contracts/src/2.0.0/test/TestSignatureValidator/TestSignatureValidator.sol b/packages/contracts/src/2.0.0/test/TestSignatureValidator/TestSignatureValidator.sol
index e1a610469..ea3e2de59 100644
--- a/packages/contracts/src/2.0.0/test/TestSignatureValidator/TestSignatureValidator.sol
+++ b/packages/contracts/src/2.0.0/test/TestSignatureValidator/TestSignatureValidator.sol
@@ -26,7 +26,6 @@ contract TestSignatureValidator is
     MixinSignatureValidator,
     MixinTransactions
 {
-
     function publicIsValidSignature(
         bytes32 hash,
         address signer,
diff --git a/packages/contracts/src/2.0.0/tokens/ERC20Token/ERC20Token.sol b/packages/contracts/src/2.0.0/tokens/ERC20Token/ERC20Token.sol
index 5ef5ee7ce..725d304df 100644
--- a/packages/contracts/src/2.0.0/tokens/ERC20Token/ERC20Token.sol
+++ b/packages/contracts/src/2.0.0/tokens/ERC20Token/ERC20Token.sol
@@ -24,7 +24,6 @@ import "./IERC20Token.sol";
 contract ERC20Token is
     IERC20Token
 {
-
     mapping (address => uint256) internal balances;
     mapping (address => mapping (address => uint256)) internal allowed;
 
diff --git a/packages/contracts/src/2.0.0/tokens/ERC20Token/MintableERC20Token.sol b/packages/contracts/src/2.0.0/tokens/ERC20Token/MintableERC20Token.sol
index cd1c7b4bb..9dc924422 100644
--- a/packages/contracts/src/2.0.0/tokens/ERC20Token/MintableERC20Token.sol
+++ b/packages/contracts/src/2.0.0/tokens/ERC20Token/MintableERC20Token.sol
@@ -26,7 +26,6 @@ contract MintableERC20Token is
     SafeMath,
     UnlimitedAllowanceERC20Token
 {
-
     /// @dev Mints new tokens
     /// @param _to Address of the beneficiary that will own the minted token
     /// @param _value Amount of tokens to mint
diff --git a/packages/contracts/src/2.0.0/tokens/ERC20Token/UnlimitedAllowanceERC20Token.sol b/packages/contracts/src/2.0.0/tokens/ERC20Token/UnlimitedAllowanceERC20Token.sol
index e6f7c063e..2e5bd4348 100644
--- a/packages/contracts/src/2.0.0/tokens/ERC20Token/UnlimitedAllowanceERC20Token.sol
+++ b/packages/contracts/src/2.0.0/tokens/ERC20Token/UnlimitedAllowanceERC20Token.sol
@@ -24,7 +24,6 @@ import "../ERC20Token/ERC20Token.sol";
 contract UnlimitedAllowanceERC20Token is
     ERC20Token
 {
-
     uint256 constant internal MAX_UINT = 2**256 - 1;
 
     /// @dev ERC20 transferFrom, modified such that an allowance of MAX_UINT represents an unlimited allowance. See https://github.com/ethereum/EIPs/issues/717
diff --git a/packages/contracts/src/2.0.0/tokens/ERC721Token/MintableERC721Token.sol b/packages/contracts/src/2.0.0/tokens/ERC721Token/MintableERC721Token.sol
index 85d192779..bc5cd2cc2 100644
--- a/packages/contracts/src/2.0.0/tokens/ERC721Token/MintableERC721Token.sol
+++ b/packages/contracts/src/2.0.0/tokens/ERC721Token/MintableERC721Token.sol
@@ -24,7 +24,6 @@ import "./ERC721Token.sol";
 contract MintableERC721Token is
     ERC721Token
 {
-
     /// @dev Function to mint a new token
     ///      Reverts if the given token ID already exists
     /// @param _to Address of the beneficiary that will own the minted token
diff --git a/packages/contracts/src/2.0.0/tokens/ZRXToken/ZRXToken.sol b/packages/contracts/src/2.0.0/tokens/ZRXToken/ZRXToken.sol
index 28c0b2fb3..f4855759c 100644
--- a/packages/contracts/src/2.0.0/tokens/ZRXToken/ZRXToken.sol
+++ b/packages/contracts/src/2.0.0/tokens/ZRXToken/ZRXToken.sol
@@ -22,11 +22,13 @@ pragma solidity 0.4.11;
 import { UnlimitedAllowanceToken_v1 as UnlimitedAllowanceToken } from "../../../1.0.0/UnlimitedAllowanceToken/UnlimitedAllowanceToken_v1.sol";
 
 
-contract ZRXToken is UnlimitedAllowanceToken {
+contract ZRXToken is 
+    UnlimitedAllowanceToken
+{
 
     // solhint-disable const-name-snakecase
     uint8 constant public decimals = 18;
-    uint public totalSupply = 10**27; // 1 billion tokens, 18 decimal places
+    uint256 public totalSupply = 10**27; // 1 billion tokens, 18 decimal places
     string constant public name = "0x Protocol Token";
     string constant public symbol = "ZRX";
     // solhint-enableconst-name-snakecase
diff --git a/packages/contracts/src/2.0.0/utils/LibBytes/LibBytes.sol b/packages/contracts/src/2.0.0/utils/LibBytes/LibBytes.sol
index 504e950a8..369f588ad 100644
--- a/packages/contracts/src/2.0.0/utils/LibBytes/LibBytes.sol
+++ b/packages/contracts/src/2.0.0/utils/LibBytes/LibBytes.sol
@@ -188,7 +188,8 @@ library LibBytes {
         memCopy(
             result.contentAddress(),
             b.contentAddress() + from,
-            result.length);
+            result.length
+        );
         return result;
     }
     
@@ -433,7 +434,8 @@ library LibBytes {
         pure
         returns (uint256 result)
     {
-        return uint256(readBytes32(b, index));
+        result = uint256(readBytes32(b, index));
+        return result;
     }
 
     /// @dev Writes a uint256 into a specific position in a byte array.
@@ -467,8 +469,13 @@ library LibBytes {
             b.length >= index + 4,
             "GREATER_OR_EQUAL_TO_4_LENGTH_REQUIRED"
         );
+
+        // Arrays are prefixed by a 32 byte length field
+        index += 32;
+
+        // Read the bytes4 from array memory
         assembly {
-            result := mload(add(b, 32))
+            result := mload(add(b, index))
             // Solidity does not require us to clean the trailing bytes.
             // We do it anyway
             result := and(result, 0xFFFFFFFF00000000000000000000000000000000000000000000000000000000)
diff --git a/packages/contracts/src/2.0.0/utils/Ownable/IOwnable.sol b/packages/contracts/src/2.0.0/utils/Ownable/IOwnable.sol
index 116b8dc89..5deb13497 100644
--- a/packages/contracts/src/2.0.0/utils/Ownable/IOwnable.sol
+++ b/packages/contracts/src/2.0.0/utils/Ownable/IOwnable.sol
@@ -1,13 +1,8 @@
 pragma solidity 0.4.24;
 
-/*
- * Ownable
- *
- * Base contract with an owner.
- * Provides onlyOwner modifier, which prevents function from running if it is called by anyone other than the owner.
- */
 
 contract IOwnable {
+
     function transferOwnership(address newOwner)
         public;
 }
diff --git a/packages/contracts/src/2.0.0/utils/Ownable/Ownable.sol b/packages/contracts/src/2.0.0/utils/Ownable/Ownable.sol
index aca65aad2..0c830be68 100644
--- a/packages/contracts/src/2.0.0/utils/Ownable/Ownable.sol
+++ b/packages/contracts/src/2.0.0/utils/Ownable/Ownable.sol
@@ -1,16 +1,11 @@
 pragma solidity 0.4.24;
 
-/*
- * Ownable
- *
- * Base contract with an owner.
- * Provides onlyOwner modifier, which prevents function from running if it is called by anyone other than the owner.
- */
-
 import "./IOwnable.sol";
 
 
-contract Ownable is IOwnable {
+contract Ownable is
+    IOwnable
+{
     address public owner;
 
     constructor ()
diff --git a/packages/contracts/src/2.0.0/utils/ReentrancyGuard/ReentrancyGuard.sol b/packages/contracts/src/2.0.0/utils/ReentrancyGuard/ReentrancyGuard.sol
index 1dee512d4..9f98a7a16 100644
--- a/packages/contracts/src/2.0.0/utils/ReentrancyGuard/ReentrancyGuard.sol
+++ b/packages/contracts/src/2.0.0/utils/ReentrancyGuard/ReentrancyGuard.sol
@@ -15,6 +15,7 @@
   limitations under the License.
 
 */
+
 pragma solidity 0.4.24;
 
 
diff --git a/packages/contracts/src/2.0.0/utils/SafeMath/SafeMath.sol b/packages/contracts/src/2.0.0/utils/SafeMath/SafeMath.sol
index 63a2a085f..2855edb9d 100644
--- a/packages/contracts/src/2.0.0/utils/SafeMath/SafeMath.sol
+++ b/packages/contracts/src/2.0.0/utils/SafeMath/SafeMath.sol
@@ -2,6 +2,7 @@ pragma solidity 0.4.24;
 
 
 contract SafeMath {
+
     function safeMul(uint256 a, uint256 b)
         internal
         pure