diff --git a/src/opensesim/world/World.java b/src/opensesim/world/World.java
index cf8772f..e0b6a2d 100644
--- a/src/opensesim/world/World.java
+++ b/src/opensesim/world/World.java
@@ -51,4 +51,6 @@ public interface World {
     public float randNextFloat(float min, float max);
     
     public long currentTimeMillis();
+    
+    public AssetPair getAssetPair(AbstractAsset asset, AbstractAsset currency);
 }