-periodic watcher, ever, or make any event loop modificstions</i>. If you need
-to stop it, return 1e30 (or so, fudge fudge) and stop it afterwards.</p>
+periodic watcher, ever, or make any event loop modifications</i>. If you need
+to stop it, return <code>now + 1e30</code> (or so, fudge fudge) and stop it afterwards.</p>
+ <p>Also, <i><this callback must always return a time that is later than the
+passed <code>now</code> value </i>>. Not even <code>now</code> itself will be ok.</p>