Index: src/wp-includes/capabilities.php
===================================================================
--- src/wp-includes/capabilities.php	(revision 26097)
+++ src/wp-includes/capabilities.php	(working copy)
@@ -378,6 +378,15 @@
 	 * @return bool True, if user has capability. False, if doesn't have capability.
 	 */
 	function has_cap( $cap ) {
+		/**
+		 * Filter which capabilities a role has.
+		 *
+		 * @since 2.0.0
+		 *
+		 * @param array  $capabilities Array of role capabilities.
+		 * @param string $cap          Capability name.
+		 * @param string $name         Role name.
+		 */
 		$capabilities = apply_filters( 'role_has_cap', $this->capabilities, $cap, $this->name );
 		if ( !empty( $capabilities[$cap] ) )
 			return $capabilities[$cap];
@@ -822,6 +831,17 @@
 		update_user_meta( $this->ID, $this->cap_key, $this->caps );
 		$this->get_role_caps();
 		$this->update_user_level_from_caps();
+
+		/**
+		 * Fires after the user's role has changed.
+		 *
+		 * @since 2.9.0
+		 * @since 3.6.0 Added $old_roles to include an array of the user's previous roles.
+		 *
+		 * @param int    $user_id   The user ID.
+		 * @param string $role      The new role.
+		 * @param array  $old_roles An array of the user's previous roles.
+		 */
 		do_action( 'set_user_role', $this->ID, $role, $old_roles );
 	}
 
@@ -942,6 +962,17 @@
 			return true;
 		}
 
+		/**
+		 * Dynamically filter a user's capabilities.
+		 *
+		 * @since 2.0.0
+		 * @since 3.7.0 Added the user object.
+		 *
+		 * @param array   $allcaps An array of all the role's capabilities.
+		 * @param array   $caps    Actual capabilities for meta capability.
+		 * @param array   $args    Optional parameters passed to has_cap(), typically object ID.
+		 * @param WP_User $user    The user object.
+		 */
 		// Must have ALL requested caps
 		$capabilities = apply_filters( 'user_has_cap', $this->allcaps, $caps, $args, $this );
 		$capabilities['exist'] = true; // Everyone is allowed to exist
@@ -1170,6 +1201,21 @@
 		$meta_key = isset( $args[ 1 ] ) ? $args[ 1 ] : false;
 
 		if ( $meta_key && has_filter( "auth_post_meta_{$meta_key}" ) ) {
+			/**
+			 * Filter whether the user is allowed to add post meta to a post.
+			 *
+			 * The dynamic portion of the hook name, $meta_key, refers to the
+			 * meta key passed to map_meta_cap().
+			 *
+			 * @since 3.3.0
+			 *
+			 * @param bool   $allowed  Whether the user can add the post meta. Default false.
+			 * @param string $meta_key The meta key.
+			 * @param int    $post_id  Post ID.
+			 * @param int    $user_id  User ID.
+			 * @param string $cap      Capability name.
+			 * @param array  $caps     User capabilities.
+			 */
 			$allowed = apply_filters( "auth_post_meta_{$meta_key}", false, $meta_key, $post->ID, $user_id, $cap, $caps );
 			if ( ! $allowed )
 				$caps[] = $cap;
@@ -1271,7 +1317,17 @@
 		$caps[] = $cap;
 	}
 
-	return apply_filters('map_meta_cap', $caps, $cap, $user_id, $args);
+	/**
+	 * Filter a user's capabilities depending on specific context and/or privilege.
+	 *
+	 * @since 2.8.0
+	 *
+	 * @param array  $caps    Returns the user's actual capabilities.
+	 * @param string $cap     Capability name
+	 * @param int    $user_id The user ID.
+	 * @param array  $args    Adds the context to the cap. Typically the object ID.
+	 */
+	return apply_filters( 'map_meta_cap', $caps, $cap, $user_id, $args );
 }
 
 /**