diff --git a/modules/purchase_trade/purchase.py b/modules/purchase_trade/purchase.py
index 54df54c..052225a 100755
--- a/modules/purchase_trade/purchase.py
+++ b/modules/purchase_trade/purchase.py
@@ -279,6 +279,11 @@ class Purchase(metaclass=PoolMeta):
     tol_max_qt = fields.Numeric("Tol +")
     tolerance_used = fields.Function(
         fields.Numeric("Tolerance used"), 'get_tolerance_used')
+    tolerance_option = fields.Selection([
+        ('no_option', "No option"),
+        ('buyer_option', "Buyer's option"),
+        ('seller_option', "Seller's option"),
+        ], "Tolerance option")
     tolerance_min = fields.Function(
         fields.Numeric("Tolerance min"), 'get_tolerance_min')
     tolerance_max = fields.Function(
@@ -401,6 +406,10 @@ class Purchase(metaclass=PoolMeta):
     def default_tol_max(cls):
         return 0
 
+    @classmethod
+    def default_tolerance_option(cls):
+        return 'no_option'
+
     def _line_quantity_in_unit(self, quantity, from_unit, to_unit):
         if not from_unit or not to_unit or from_unit == to_unit:
             return Decimal(str(quantity or 0))
diff --git a/modules/purchase_trade/sale.py b/modules/purchase_trade/sale.py
index 78ac338..24fd836 100755
--- a/modules/purchase_trade/sale.py
+++ b/modules/purchase_trade/sale.py
@@ -251,6 +251,11 @@ class Sale(metaclass=PoolMeta):
     tol_max_qt = fields.Numeric("Tol +")
     tolerance_used = fields.Function(
         fields.Numeric("Tolerance used"), 'get_tolerance_used')
+    tolerance_option = fields.Selection([
+        ('no_option', "No option"),
+        ('buyer_option', "Buyer's option"),
+        ('seller_option', "Seller's option"),
+        ], "Tolerance option")
     tolerance_min = fields.Function(
         fields.Numeric("Tolerance min"), 'get_tolerance_min')
     tolerance_max = fields.Function(
@@ -365,6 +370,10 @@ class Sale(metaclass=PoolMeta):
     def default_tol_max(cls):
         return 0
 
+    @classmethod
+    def default_tolerance_option(cls):
+        return 'no_option'
+
     def _line_quantity_in_unit(self, quantity, from_unit, to_unit):
         if not from_unit or not to_unit or from_unit == to_unit:
             return abs(Decimal(str(quantity or 0)))
diff --git a/modules/purchase_trade/tests/test_module.py b/modules/purchase_trade/tests/test_module.py
index 6795c01..38ad64a 100644
--- a/modules/purchase_trade/tests/test_module.py
+++ b/modules/purchase_trade/tests/test_module.py
@@ -1776,6 +1776,14 @@ class PurchaseTradeTestCase(ModuleTestCase):
         self.assertEqual(
             Purchase.operator.domain, [('categories.name', '=', 'OPERATOR')])
 
+    def test_sale_and_purchase_tolerance_option_defaults_to_no_option(self):
+        'sale and purchase tolerance option defaults to no option'
+        Sale = Pool().get('sale.sale')
+        Purchase = Pool().get('purchase.purchase')
+
+        self.assertEqual(Sale.default_tolerance_option(), 'no_option')
+        self.assertEqual(Purchase.default_tolerance_option(), 'no_option')
+
     def test_sale_line_basis_price_and_progress_use_manual_summary_without_component(self):
         'sale line basis values use manual summary rows even without a component'
         SaleLine = Pool().get('sale.line')
diff --git a/modules/purchase_trade/view/purchase_form.xml b/modules/purchase_trade/view/purchase_form.xml
index 8d8dd5e..23c8190 100755
--- a/modules/purchase_trade/view/purchase_form.xml
+++ b/modules/purchase_trade/view/purchase_form.xml
@@ -36,6 +36,8 @@ this repository contains the full copyright notices and license terms. -->
         <field name="tolerance_used" widget="tolerance_gauge"
             min_field="tolerance_min" max_field="tolerance_max"
             xexpand="1" xfill="1"/>
+        <label name="tolerance_option"/>
+        <field name="tolerance_option"/>
         <field name="tolerance_min" invisible="1"/>
         <field name="tolerance_max" invisible="1"/>
         <newline/>
diff --git a/modules/purchase_trade/view/sale_form.xml b/modules/purchase_trade/view/sale_form.xml
index 33d5f96..9b96597 100755
--- a/modules/purchase_trade/view/sale_form.xml
+++ b/modules/purchase_trade/view/sale_form.xml
@@ -36,6 +36,8 @@ this repository contains the full copyright notices and license terms. -->
         <field name="tolerance_used" widget="tolerance_gauge"
             min_field="tolerance_min" max_field="tolerance_max"
             xexpand="1" xfill="1"/>
+        <label name="tolerance_option"/>
+        <field name="tolerance_option"/>
         <field name="tolerance_min" invisible="1"/>
         <field name="tolerance_max" invisible="1"/>
         <newline/>