title: Add alert to iCal data/calendar Object
body: <p>I created a URL that opens the calendar App on iOS devices, with some predefined info. This is my code:</p>
  
  <pre><code>window.location = encodeURI(
    'data:text/calendar;charset=utf8,' +
      [
        'BEGIN:VCALENDAR',
        'VERSION:2.0',
        'BEGIN:VEVENT',
        'URL:' + document.URL,
        'DTSTART:' + formatTime(startDate),
        'DTEND:' + formatTime(endDate),
        'SUMMARY:' + eventName,
        'DESCRIPTION:' + description,
        'LOCATION:' + location,
        'END:VEVENT',
        'END:VCALENDAR',
        'TRIGGER:-P15M'
      ].join('\n')
  );
  </code></pre>
  
  <p>Ignoring all the variables, it works fine. The only thing not working is the alert. By default, when it opens it says alert: "None". I want a 15 minute alert by default.</p>
  
  <p>I tried using "TRIGGER:-P15M" but it didn't work. Is it possible to do so?</p>