Replaced protocolFeePaid -> protocolFeeAmount. Changed some wording in comments.

contracts/staking/contracts/src/fees/MixinExchangeFees.sol

@@ -41,17 +41,17 @@ contract MixinExchangeFees is
     ///      (MixinExchangeManager).
     /// @param makerAddress The address of the order's maker.
     /// @param payerAddress The address of the protocol fee payer.
-    /// @param protocolFeePaid The protocol fee that should be paid.
+    /// @param protocolFee The protocol fee amount. This is either passed as ETH or transferred as WETH.
     function payProtocolFee(
         address makerAddress,
         address payerAddress,
-        uint256 protocolFeePaid
+        uint256 protocolFee
     )
         external
         payable
         onlyExchange
     {
-        _assertValidProtocolFee(protocolFeePaid);
+        _assertValidProtocolFee(protocolFee);
 
         // Transfer the protocol fee to this address if it should be paid in
         // WETH.
@@ -60,7 +60,7 @@ contract MixinExchangeFees is
                 getWethContract().transferFrom(
                     payerAddress,
                     address(this),
-                    protocolFeePaid
+                    protocolFee
                 ),
                 "WETH_TRANSFER_FAILED"
             );
@@ -106,10 +106,10 @@ contract MixinExchangeFees is
         }
 
         // Credit the fees to the pool.
-        poolStatsPtr.feesCollected = feesCollectedByPool.safeAdd(protocolFeePaid);
+        poolStatsPtr.feesCollected = feesCollectedByPool.safeAdd(protocolFee);
 
         // Increase the total fees collected this epoch.
-        aggregatedStatsPtr.totalFeesCollected = aggregatedStatsPtr.totalFeesCollected.safeAdd(protocolFeePaid);
+        aggregatedStatsPtr.totalFeesCollected = aggregatedStatsPtr.totalFeesCollected.safeAdd(protocolFee);
     }
 
     /// @dev Get stats on a staking pool in this epoch.
@@ -155,18 +155,18 @@ contract MixinExchangeFees is
 
     /// @dev Checks that the protocol fee passed into `payProtocolFee()` is
     ///      valid.
-    /// @param protocolFeePaid The `protocolFeePaid` parameter to
+    /// @param protocolFee The `protocolFee` parameter to
     ///        `payProtocolFee.`
-    function _assertValidProtocolFee(uint256 protocolFeePaid)
+    function _assertValidProtocolFee(uint256 protocolFee)
         private
         view
     {
         // The protocol fee must equal the value passed to the contract; unless
         // the value is zero, in which case the fee is taken in WETH.
-        if (msg.value != protocolFeePaid && msg.value != 0) {
+        if (msg.value != protocolFee && msg.value != 0) {
             LibRichErrors.rrevert(
                 LibStakingRichErrors.InvalidProtocolFeePaymentError(
-                    protocolFeePaid,
+                    protocolFee,
                     msg.value
                 )
             );

contracts/staking/contracts/src/interfaces/IStaking.sol

@@ -40,11 +40,11 @@ interface IStaking {
     /// @dev Pays a protocol fee in ETH.
     /// @param makerAddress The address of the order's maker.
     /// @param payerAddress The address that is responsible for paying the protocol fee.
-    /// @param protocolFeePaid The amount of protocol fees that should be paid.
+    /// @param protocolFee The amount of protocol fees that should be paid.
     function payProtocolFee(
         address makerAddress,
         address payerAddress,
-        uint256 protocolFeePaid
+        uint256 protocolFee
     )
         external
         payable;

contracts/staking/contracts/src/stake/MixinStake.sol

@@ -178,19 +178,19 @@ contract MixinStake is
             staker
         );
 
-        // Increment how much stake the staker has delegated to the input pool.
+        // Increase how much stake the staker has delegated to the input pool.
         _increaseNextBalance(
             _delegatedStakeToPoolByOwner[staker][poolId],
             amount
         );
 
-        // Increment how much stake has been delegated to pool.
+        // Increase how much stake has been delegated to pool.
         _increaseNextBalance(
             _delegatedStakeByPoolId[poolId],
             amount
         );
 
-        // Increase next balance of global delegated stake
+        // Increase next balance of global delegated stake.
         _increaseNextBalance(
             _globalStakeByStatus[uint8(IStructs.StakeStatus.DELEGATED)],
             amount
@@ -216,19 +216,19 @@ contract MixinStake is
             staker
         );
 
-        // decrement how much stake the staker has delegated to the input pool
+        // Decrease how much stake the staker has delegated to the input pool.
         _decreaseNextBalance(
             _delegatedStakeToPoolByOwner[staker][poolId],
             amount
         );
 
-        // decrement how much stake has been delegated to pool
+        // Decrease how much stake has been delegated to pool.
         _decreaseNextBalance(
             _delegatedStakeByPoolId[poolId],
             amount
         );
 
-        // decrease next balance of global delegated stake
+        // Decrease next balance of global delegated stake (aggregated across all stakers).
         _decreaseNextBalance(
             _globalStakeByStatus[uint8(IStructs.StakeStatus.DELEGATED)],
             amount

contracts/staking/test/unit_tests/protocol_fees_test.ts

@@ -90,7 +90,7 @@ blockchainTests('Protocol Fees unit tests', env => {
                 return expect(tx).to.revertWith(expectedError);
             });
 
-            it('should revert if `protocolFeePaid` is zero with non-zero value sent', async () => {
+            it('should revert if `protocolFee` is zero with non-zero value sent', async () => {
                 const tx = testContract.payProtocolFee.awaitTransactionSuccessAsync(
                     makerAddress,
                     payerAddress,
@@ -104,7 +104,7 @@ blockchainTests('Protocol Fees unit tests', env => {
                 return expect(tx).to.revertWith(expectedError);
             });
 
-            it('should revert if `protocolFeePaid` is < than the provided message value', async () => {
+            it('should revert if `protocolFee` is < than the provided message value', async () => {
                 const tx = testContract.payProtocolFee.awaitTransactionSuccessAsync(
                     makerAddress,
                     payerAddress,
@@ -118,7 +118,7 @@ blockchainTests('Protocol Fees unit tests', env => {
                 return expect(tx).to.revertWith(expectedError);
             });
 
-            it('should revert if `protocolFeePaid` is > than the provided message value', async () => {
+            it('should revert if `protocolFee` is > than the provided message value', async () => {
                 const tx = testContract.payProtocolFee.awaitTransactionSuccessAsync(
                     makerAddress,
                     payerAddress,

contracts/staking/test/utils/cumulative_reward_tracking_simulation.ts

@@ -24,7 +24,7 @@ interface TestLog {
 
 export class CumulativeRewardTrackingSimulation {
     private readonly _amountToStake = toBaseUnitAmount(100);
-    private readonly _protocolFeeAmount = new BigNumber(10);
+    private readonly _protocolFee = new BigNumber(10);
     private readonly _stakingApiWrapper: StakingApiWrapper;
     private readonly _staker: string;
     private readonly _poolOperator: string;
@@ -141,8 +141,8 @@ export class CumulativeRewardTrackingSimulation {
                     receipt = await this._stakingApiWrapper.stakingContract.payProtocolFee.awaitTransactionSuccessAsync(
                         this._poolOperator,
                         this._takerAddress,
-                        this._protocolFeeAmount,
+                        this._protocolFee,
-                        { from: this._exchangeAddress, value: this._protocolFeeAmount },
+                        { from: this._exchangeAddress, value: this._protocolFee },
                     );
                     break;