diff --git a/src/Alert/Reactor.php b/src/Alert/Reactor.php
index f15e3e5..26e0d6b 100755
--- a/src/Alert/Reactor.php
+++ b/src/Alert/Reactor.php
@@ -22,6 +22,9 @@ interface Reactor {
     /**
      * Schedule a callback for immediate invocation in the next event loop iteration
      *
+     * Though it can't be enforced at the interface level all timer/stream scheduling methods
+     * should return a unique integer identifying the relevant watcher.
+     *
      * @param callable $callback Any valid PHP callable
      */
     function immediately(callable $callback);
@@ -29,6 +32,12 @@ interface Reactor {
     /**
      * Schedule a callback to execute once
      *
+     * Time intervals are measured in seconds. Floating point values < 0 denote intervals less than
+     * one second. e.g. $interval = 0.001 means a one millisecond interval.
+     *
+     * Though it can't be enforced at the interface level all timer/stream scheduling methods
+     * should return a unique integer identifying the relevant watcher.
+     *
      * @param callable $callback Any valid PHP callable
      * @param float $delay The delay in seconds before the callback will be invoked (zero is allowed)
      */
@@ -37,6 +46,12 @@ interface Reactor {
     /**
      * Schedule a recurring callback to execute every $interval seconds until cancelled
      *
+     * Time intervals are measured in seconds. Floating point values < 0 denote intervals less than
+     * one second. e.g. $interval = 0.001 means a one millisecond interval.
+     *
+     * Though it can't be enforced at the interface level all timer/stream scheduling methods
+     * should return a unique integer identifying the relevant watcher.
+     *
      * @param callable $callback Any valid PHP callable
      * @param float $interval The interval in seconds to observe between callback executions (zero is allowed)
      */
@@ -45,6 +60,9 @@ interface Reactor {
     /**
      * Schedule an event to trigger once at the specified time
      *
+     * Though it can't be enforced at the interface level all timer/stream scheduling methods
+     * should return a unique integer identifying the relevant watcher.
+     *
      * @param callable $callback Any valid PHP callable
      * @param string $timeString Any string that can be parsed by strtotime() and is in the future
      */
@@ -53,6 +71,9 @@ interface Reactor {
     /**
      * Watch a stream resource for IO readable data and trigger the callback when actionable
      *
+     * Though it can't be enforced at the interface level all timer/stream scheduling methods
+     * should return a unique integer identifying the relevant watcher.
+     *
      * @param resource $stream A stream resource to watch for readable data
      * @param callable $callback Any valid PHP callable
      * @param bool $enableNow Should the watcher be enabled now or held for later use?
@@ -62,6 +83,9 @@ interface Reactor {
     /**
      * Watch a stream resource to become writable and trigger the callback when actionable
      *
+     * Though it can't be enforced at the interface level all timer/stream scheduling methods
+     * should return a unique integer identifying the relevant watcher.
+     *
      * @param resource $stream A stream resource to watch for writability
      * @param callable $callback Any valid PHP callable
      * @param bool $enableNow Should the watcher be enabled now or held for later use?