Index: src/sas/sasgui/guiframe/dataFitting.py
===================================================================
--- src/sas/sasgui/guiframe/dataFitting.py	(revision 345e7e4a8c6f5977c8c07032553b5ab00bdf837d)
+++ src/sas/sasgui/guiframe/dataFitting.py	(revision 68adf86632754e28ed4e1600ebe337656f349a2b)
@@ -17,5 +17,6 @@
     """
     """
-    def __init__(self, x=None, y=None, dx=None, dy=None):
+
+    def __init__(self, x=None, y=None, dx=None, dy=None, lam=None, dlam=None, isSesans=False):
         """
         """
@@ -24,6 +25,8 @@
         if y is None:
             y = []
-        PlotData1D.__init__(self, x, y, dx, dy)
-        LoadData1D.__init__(self, x, y, dx, dy)
+        self.isSesans = isSesans
+        PlotData1D.__init__(self, x, y, dx, dy, lam, dlam)
+        LoadData1D.__init__(self, x, y, dx, dy, lam, dlam, isSesans)
+
         self.id = None
         self.list_group_id = []
@@ -32,5 +35,9 @@
         self.path = None
         self.xtransform = None
+        if self.isSesans:
+            self.xtransform = "x"
         self.ytransform = None
+        if self.isSesans:
+            self.ytransform = "y"
         self.title = ""
         self.scale = None
@@ -68,5 +75,5 @@
         # First, check the data compatibility
         dy, dy_other = self._validity_check(other)
-        result = Data1D(x=[], y=[], dx=None, dy=None)
+        result = Data1D(x=[], y=[], lam=[], dx=None, dy=None, dlam=None)
         result.clone_without_data(length=len(self.x), clone=self)
         result.copy_from_datainfo(data1d=self)
@@ -115,7 +122,11 @@
         # First, check the data compatibility
         self._validity_check_union(other)
-        result = Data1D(x=[], y=[], dx=None, dy=None)
+        result = Data1D(x=[], y=[], lam=[], dx=None, dy=None, dlam=None)
         tot_length = len(self.x) + len(other.x)
         result = self.clone_without_data(length=tot_length, clone=result)
+        if self.dlam == None or other.dlam is None:
+            result.dlam = None
+        else:
+            result.dlam = numpy.zeros(tot_length)
         if self.dy == None or other.dy is None:
             result.dy = None
@@ -141,4 +152,9 @@
         result.y = numpy.append(self.y, other.y)
         result.y = result.y[ind]
+        result.lam = numpy.append(self.lam, other.lam)
+        result.lam = result.lam[ind]
+        if result.dlam != None:
+            result.dlam = numpy.append(self.dlam, other.dlam)
+            result.dlam = result.dlam[ind]
         if result.dy != None:
             result.dy = numpy.append(self.dy, other.dy)
@@ -260,7 +276,11 @@
         # First, check the data compatibility
         self._validity_check_union(other)
-        result = Data1D(x=[], y=[], dx=None, dy=None)
+        result = Data1D(x=[], y=[], lam=[], dx=None, dy=None, dlam=[])
         tot_length = len(self.x)+len(other.x)
         result.clone_without_data(length=tot_length, clone=self)
+        if self.dlam == None or other.dlam is None:
+            result.dlam = None
+        else:
+            result.dlam = numpy.zeros(tot_length)
         if self.dy == None or other.dy is None:
             result.dy = None
@@ -285,4 +305,6 @@
         result.y = numpy.append(self.y, other.y)
         result.y = result.y[ind]
+        result.lam = numpy.append(self.lam, other.lam)
+        result.lam = result.lam[ind]
         if result.dy != None:
             result.dy = numpy.append(self.dy, other.dy)
Index: src/sas/sasgui/guiframe/data_manager.py
===================================================================
--- src/sas/sasgui/guiframe/data_manager.py	(revision 345e7e4a8c6f5977c8c07032553b5ab00bdf837d)
+++ src/sas/sasgui/guiframe/data_manager.py	(revision 20522e12c1673e2938cba2e95b8857993da746ce)
@@ -61,8 +61,14 @@
         
         if issubclass(Data2D, data.__class__):
-            new_plot = Data2D(image=None, err_image=None) 
-        else: 
-            new_plot = Data1D(x=[], y=[], dx=None, dy=None)
-           
+            new_plot = Data2D(image=None, err_image=None, isSesans=data.isSesans) # For now, isSesans for 2D data is always false
+        else:
+            new_plot = Data1D(x=[], y=[], dx=None, dy=None, lam=None, dlam=None, isSesans=data.isSesans)
+
+
+        #elif data.meta_data['loader'] == 'SESANS':
+        #    new_plot = Data1D(x=[], y=[], dx=None, dy=None, lam=None, dlam=None, isSesans=True)
+        #else:
+        #    new_plot = Data1D(x=[], y=[], dx=None, dy=None, lam=None, dlam=None) #SESANS check???
+
         new_plot.copy_from_datainfo(data)
         data.clone_without_data(clone=new_plot)
