diff --git a/planetstack/core/models/plcorebase.py b/planetstack/core/models/plcorebase.py
index 62bcb75..08e4047 100644
--- a/planetstack/core/models/plcorebase.py
+++ b/planetstack/core/models/plcorebase.py
@@ -6,52 +6,53 @@
 
 class PlCoreBase(models.Model):
 
-	created = models.DateTimeField(auto_now_add=True)
-	updated = models.DateTimeField(auto_now=True)
+    created = models.DateTimeField(auto_now_add=True)
+    updated = models.DateTimeField(auto_now=True)
+    enacted = models.DateTimeField(null=True, default=None)
 
-	class Meta:
-		abstract = True
-		app_label = "core"
+    class Meta:
+        abstract = True
+        app_label = "core"
 
-	def __init__(self, *args, **kwargs):
-		super(PlCoreBase, self).__init__(*args, **kwargs)
-		self.__initial = self._dict
+    def __init__(self, *args, **kwargs):
+        super(PlCoreBase, self).__init__(*args, **kwargs)
+        self.__initial = self._dict
 
-	@property
-	def diff(self):
-		d1 = self.__initial
-		d2 = self._dict
-		diffs = [(k, (v, d2[k])) for k, v in d1.items() if v != d2[k]]
-		return dict(diffs)
+    @property
+    def diff(self):
+        d1 = self.__initial
+        d2 = self._dict
+        diffs = [(k, (v, d2[k])) for k, v in d1.items() if v != d2[k]]
+        return dict(diffs)
 
-	@property
-	def has_changed(self):
-		return bool(self.diff)
+    @property
+    def has_changed(self):
+        return bool(self.diff)
 
-	@property
-	def changed_fields(self):
-		return self.diff.keys()
+    @property
+    def changed_fields(self):
+        return self.diff.keys()
 
-	def get_field_diff(self, field_name):
-		return self.diff.get(field_name, None)
+    def get_field_diff(self, field_name):
+        return self.diff.get(field_name, None)
 
-	def delete(self, *args, **kwds):
-		super(PlCoreBase, self).delete(*args, **kwds)
+    def delete(self, *args, **kwds):
+        super(PlCoreBase, self).delete(*args, **kwds)
 
-		EventSender().fire({'delete_flag':True,'model':self.__name__})
+        EventSender().fire({'delete_flag':True,'model':self.__name__})
 
-	def save(self, *args, **kwargs):
-		super(PlCoreBase, self).save(*args, **kwargs)
-		
-		# Tell the observer that the source database has been updated
-		EventSender().fire()
+    def save(self, *args, **kwargs):
+        super(PlCoreBase, self).save(*args, **kwargs)
+        
+        # Tell the observer that the source database has been updated
+        EventSender().fire()
 
-		self.__initial = self._dict
+        self.__initial = self._dict
 
-	@property
-	def _dict(self):
-		return model_to_dict(self, fields=[field.name for field in
-							 self._meta.fields])
+    @property
+    def _dict(self):
+        return model_to_dict(self, fields=[field.name for field in
+                             self._meta.fields])