diff -r 86d805a56843 -r 7e3156578f28 annot-server/webapp/admin.py
--- a/annot-server/webapp/admin.py	Wed Oct 22 08:53:33 2014 +0200
+++ b/annot-server/webapp/admin.py	Wed Oct 22 09:18:15 2014 +0200
@@ -90,9 +90,17 @@
 class StartTSField(dateutil_fields.DateTimeField):
     def __init__(self, *args, **kwargs):
         if 'display_format' not in kwargs:
-            kwargs['display_format']='%Y-%m-%dT%H:%M:%S.%f%z'
+            kwargs['display_format']='iso'
         super(StartTSField, self).__init__(*args, **kwargs)
 
+    def _value(self):
+        if self.raw_data:
+            return ' '.join(self.raw_data)
+        elif self.display_format == 'iso':
+            return self.data and self.data.isoformat() or ''
+        else:
+            return self.data and self.data.strftime(self.display_format) or ''
+
     def process_formdata(self, valuelist):
         super(StartTSField, self).process_formdata(valuelist)
         if self.data and self.data.tzinfo is None: