BEGIN:VCALENDAR
PRODID:drupal-calendar-ror
VERSION:2.0
{% for nid, node in ror.calendar.nodes %}

BEGIN:VEVENT
SUMMARY: {{node.title.0.value}}
UID: node-{{node.nid.0.value}}@www.ondarossa.info
DTSTAMP: {{node.created.0.value}}
DTSTART: {{node.field_data_evento.0.value|date("Ymd\\THis")}}Z
DURATION: PT1H
URL: http://www.ondarossa.info{{node.path.0.alias}}
END:VEVENT
{% endfor %}
END:VCALENDAR