diff --git a/src/anemoi/transform/sources/mars.py b/src/anemoi/transform/sources/mars.py
index 06fc48f..41ea5e0 100644
--- a/src/anemoi/transform/sources/mars.py
+++ b/src/anemoi/transform/sources/mars.py
@@ -36,6 +36,3 @@ def forward(self, data):
                 return this.forward(self.data)
 
         return Input(data)
-
-
-source_registry.register("mars", Mars)
diff --git a/src/anemoi/transform/variables/__init__.py b/src/anemoi/transform/variables/__init__.py
index 830d6ae..a0e98e1 100644
--- a/src/anemoi/transform/variables/__init__.py
+++ b/src/anemoi/transform/variables/__init__.py
@@ -83,3 +83,10 @@ def is_computed_forcing(self):
     @property
     def is_from_input(self):
         pass
+
+    def similarity(self, other):
+        """Compute the similarity between two variables. This is used when
+        encoding a variables in GRIB and we do not have a template for it.
+        We can then try to find the most similar variable for which we have a template.
+        """
+        return 0
diff --git a/src/anemoi/transform/variables/variables.py b/src/anemoi/transform/variables/variables.py
index cb74ee9..aa64b08 100644
--- a/src/anemoi/transform/variables/variables.py
+++ b/src/anemoi/transform/variables/variables.py
@@ -51,6 +51,21 @@ def is_instantanous(self):
     def grib_keys(self):
         return self.data.get("mars", {}).copy()
 
+    def similarity(self, other):
+        if not isinstance(other, VariableFromMarsVocabulary):
+            return 0
+
+        def __similarity(a, b):
+            if isinstance(a, dict) and isinstance(b, dict):
+                return sum(__similarity(a[k], b[k]) for k in set(a.keys()) & set(b.keys()))
+
+            if isinstance(a, list) and isinstance(b, list):
+                return sum(__similarity(a[i], b[i]) for i in range(min(len(a), len(b))))
+
+            return 1 if a == b else 0
+
+        return __similarity(self.data, other.data)
+
 
 class VariableFromDict(VariableFromMarsVocabulary):
     """A variable that is defined by a user provided dictionary."""
diff --git a/src/anemoi/transform/workflows/pipeline.py b/src/anemoi/transform/workflows/pipeline.py
index 73e29bb..86413f4 100644
--- a/src/anemoi/transform/workflows/pipeline.py
+++ b/src/anemoi/transform/workflows/pipeline.py
@@ -12,6 +12,7 @@
 from . import workflow_registry
 
 
+@workflow_registry.register("pipeline")
 class Pipeline(Workflow):
     """A simple pipeline of filters"""
 
@@ -27,6 +28,3 @@ def backward(self, data):
         for filter in reversed(self.filters):
             data = filter.backward(data)
         return data
-
-
-workflow_registry.register("pipeline", Pipeline)