diff --git a/contracts/token/ERC777/IERC777.sol b/contracts/token/ERC777/IERC777.sol
index 0ed1feff6..e3d30df3f 100644
--- a/contracts/token/ERC777/IERC777.sol
+++ b/contracts/token/ERC777/IERC777.sol
@@ -1,9 +1,34 @@
 pragma solidity ^0.5.0;
 
 /**
- * @dev Interface of the ERC777Tken standard as defined in the EIP.
+ * @dev Interface of the ERC777Token standard as defined in the EIP.
  */
 interface IERC777 {
+    /**
+     * @dev Returns the name of the token.
+     */
+    function name() external view returns (string memory);
+
+    /**
+     * @dev Returns the symbol of the token, usually a shorter version of the
+     * name.
+     */
+    function symbol() external view returns (string memory);
+
+    /**
+     * @dev Returns the smallest part of the token that is not divisible. This
+     * means all token operations (creation, movement and destruction) must have
+     * amounts that are a multiple of this number.
+     *
+     * For most token contracts, this value will equal 1.
+     */
+    function granularity() external view returns (uint256);
+
+    /**
+     * @dev Returns the amount of tokens in existence.
+     */
+    function totalSupply() external view returns (uint256);
+
     /**
      * @dev Returns the amount of tokens owned by an account (`owner`).
      */
@@ -32,11 +57,61 @@ interface IERC777 {
      */
     function burn(uint256 amount, bytes calldata data) external;
 
+    /**
+     * @devs Returns true if an account is an operator of `tokenHolder`.
+     * Operators can send and burn tokens on behalf of their owners. All
+     * accounts are their own operator.
+     *
+     * See `operatorSend` and `operatorBurn`.
+     */
+    function isOperatorFor(address operator, address tokenHolder) external view returns (bool);
+
+    /**
+     * @dev Make an account an operator of the caller.
+     *
+     * See `isOperatorFor`.
+     *
+     * Emits an `AuthorizedOperator` event.
+     *
+     * Requirements
+     *
+     * - `operator` cannot be calling address.
+     */
     function authorizeOperator(address operator) external;
 
+    /**
+     * @dev Make an account an operator of the caller.
+     *
+     * See `isOperatorFor` and `defaultOperators`.
+     *
+     * Emits a `RevokedOperator` event.
+     *
+     * Requirements
+     *
+     * - `operator` cannot be calling address.
+     */
     function revokeOperator(address operator) external;
 
+    /**
+     * @dev Returns the list of default operators. These accounts are operators
+     * for all token holders, even if `authorizeOperator` was never called on
+     * them.
+     *
+     * This list is immutable, but individual holders may revoke these via
+     *`revokeOperator`, in which case `isOperatorFor` will return false.
+     */
+    function defaultOperators() external view returns (address[] memory);
 
+    /**
+     * @dev Moves `amount` tokens from a token holder's account (`from`) to a
+     * specified recipient (`to`). The caller must be an operator of `from`.
+     *
+     * If send or receive hooks are registered for the holder and receiver,
+     * the corresponding functions will be called with `data` and
+     * `operatorData`. See `IERC777Sender` and `IERC777Recipient`.
+     *
+     * Emits a `Sent` event.
+     */
     function operatorSend(
         address from,
         address to,
@@ -45,6 +120,15 @@ interface IERC777 {
         bytes calldata operatorData
     ) external;
 
+    /**
+     * @dev Destoys `amount` tokens from a token holder's account (`from`),
+     * reducing the total supply. The caller must be an operator of `from`.
+     *
+     * If a send hook is registered for the holder, the corresponding function
+     * will be called with `data` and `operatorData`. See `IERC777Sender`.
+     *
+     * Emits a `Burned` event.
+     */
     function operatorBurn(
         address from,
         uint256 amount,
@@ -52,18 +136,6 @@ interface IERC777 {
         bytes calldata operatorData
     ) external;
 
-    function name() external view returns (string memory);
-
-    function symbol() external view returns (string memory);
-
-    function totalSupply() external view returns (uint256);
-
-    function granularity() external view returns (uint256);
-
-    function defaultOperators() external view returns (address[] memory);
-
-    function isOperatorFor(address operator, address tokenHolder) external view returns (bool);
-
     event Sent(
         address indexed operator,
         address indexed from,