diff --git a/modules/purchase_trade/purchase.py b/modules/purchase_trade/purchase.py
index 96b8981..be305ba 100755
--- a/modules/purchase_trade/purchase.py
+++ b/modules/purchase_trade/purchase.py
@@ -581,6 +581,7 @@ class AssayLine(ModelSQL, ModelView):
     is_payable = fields.Boolean("Payable")
 
 class AssayElement(ModelSQL, ModelView):
+    "Assay Element"
     __name__ = 'assay.element'
 
     name = fields.Char("Code")  # Cu, Au, As