diff --git a/tercen/model/impl.py b/tercen/model/impl.py
index 100cd5f..7a068a6 100644
--- a/tercen/model/impl.py
+++ b/tercen/model/impl.py
@@ -864,3 +864,50 @@ class GroupByRelation(GroupByRelationBase):
     def __init__(self, m=None):
         super().__init__(m)
 
+
+def removeMeta(self, key):
+    for i in range(0, len(self.meta)):
+        m = self.meta[i]
+        if m.key == key:
+            self.meta.pop(i)
+            break
+
+def hasMeta(self, key):
+    for i in range(0, len(self.meta)):
+        m = self.meta[i]
+        if m.key == key:
+            return True
+    return False
+
+
+def getMetaPair(self, key):
+    for i in range(0, len(self.meta)):
+        m = self.meta[i]
+        if m.key == key:
+            return m
+
+def getMeta(self, key, defaultValue=None):
+    for i in range(0, len(self.meta)):
+        m = self.meta[i]
+        if m.key == key:
+            return m.value
+    return defaultValue
+
+def addMeta(self, key:str, value:str):
+    p = Pair({"key":key, "value":value})
+    self.removeMeta(p.key)
+    self.meta.append(p)
+
+
+Task.removeMeta = removeMeta
+Task.addMeta = addMeta
+Task.hasMeta = hasMeta
+Task.getMetaPair = getMetaPair
+Task.getMeta = getMeta
+
+
+Document.removeMeta = removeMeta
+Document.addMeta = addMeta
+Document.hasMeta = hasMeta
+Document.getMetaPair = getMetaPair
+Document.getMeta = getMeta