diff --git a/python/obitools3/obidms/obidmscolumn/capidmscolumn.pyx b/python/obitools3/obidms/obidmscolumn/capidmscolumn.pyx
index dd22d3e..ffba429 100644
--- a/python/obitools3/obidms/obidmscolumn/capidmscolumn.pyx
+++ b/python/obitools3/obidms/obidmscolumn/capidmscolumn.pyx
@@ -1,11 +1,11 @@
 #cython: language_level=3
 
 from .capidmscolumn cimport *
-from obitools3.obidms.obidmscolumn.obidmscolumn_int.capidmscolumn_int import OBIDMS_column_int
-from obitools3.obidms.obidmscolumn.obidmscolumn_float.capidmscolumn_float import OBIDMS_column_float
-from obitools3.obidms.obidmscolumn.obidmscolumn_bool.capidmscolumn_bool import OBIDMS_column_bool
-from obitools3.obidms.obidmscolumn.obidmscolumn_char.capidmscolumn_char import OBIDMS_column_char
-from obitools3.obidms.obidmscolumn.obidmscolumn_idx.capidmscolumn_idx import OBIDMS_column_idx
+from obitools3.obidms.obidmscolumn.obidmscolumn_int.capidmscolumn_int import *
+from obitools3.obidms.obidmscolumn.obidmscolumn_float.capidmscolumn_float import *
+from obitools3.obidms.obidmscolumn.obidmscolumn_bool.capidmscolumn_bool import *
+from obitools3.obidms.obidmscolumn.obidmscolumn_char.capidmscolumn_char import *
+from obitools3.obidms.obidmscolumn.obidmscolumn_idx.capidmscolumn_idx import *
 
 
 cdef class OBIDMS_column:
@@ -88,39 +88,61 @@ cdef class OBIDMS_column:
                 type = obi_column_get_data_type_from_name(dms, column_name_b)
 
         if type == 1 :
-            column = OBIDMS_column_int(dms_name, column_name, 
-                                       create, clone, clone_data, 
-                                       version_number, type, 
-                                       nb_lines, nb_elements_per_line, 
-                                       elements_names)
+            if (create or clone) :
+                column = OBIDMS_column_int_writable(dms_name, column_name, 
+                                                    create, clone, clone_data, 
+                                                    version_number, type, 
+                                                    nb_lines, nb_elements_per_line, 
+                                                    elements_names)
+            else :
+                 column = OBIDMS_column_int_read(dms_name, column_name, 
+                                                 create, clone, clone_data, 
+                                                 version_number, type, 
+                                                 nb_lines, nb_elements_per_line, 
+                                                 elements_names)
+               
         
         elif type == 2 :
-            column = OBIDMS_column_float(dms_name, column_name, 
-                                       create, clone, clone_data, 
-                                       version_number, type, 
-                                       nb_lines, nb_elements_per_line, 
-                                       elements_names)
+            if (create or clone) :
+                column = OBIDMS_column_float_writable(dms_name, column_name, 
+                                                      create, clone, clone_data, 
+                                                      version_number, type, 
+                                                      nb_lines, nb_elements_per_line, 
+                                                      elements_names)
+            else :
+                 column = OBIDMS_column_float_read(dms_name, column_name, 
+                                                   create, clone, clone_data, 
+                                                   version_number, type, 
+                                                   nb_lines, nb_elements_per_line, 
+                                                   elements_names)
 
         elif type == 3 :
-            column = OBIDMS_column_bool(dms_name, column_name, 
-                                       create, clone, clone_data, 
-                                       version_number, type, 
-                                       nb_lines, nb_elements_per_line, 
-                                       elements_names)
+            if (create or clone) :
+                column = OBIDMS_column_bool_writable(dms_name, column_name, 
+                                                     create, clone, clone_data, 
+                                                     version_number, type, 
+                                                     nb_lines, nb_elements_per_line, 
+                                                     elements_names)
+            else :
+                 column = OBIDMS_column_bool_read(dms_name, column_name, 
+                                                  create, clone, clone_data, 
+                                                  version_number, type, 
+                                                  nb_lines, nb_elements_per_line, 
+                                                  elements_names)
 
         elif type == 4 :
-            column = OBIDMS_column_char(dms_name, column_name, 
-                                       create, clone, clone_data, 
-                                       version_number, type, 
-                                       nb_lines, nb_elements_per_line, 
-                                       elements_names)
-
-        elif type == 5 :
-            column = OBIDMS_column_idx(dms_name, column_name, 
-                                       create, clone, clone_data, 
-                                       version_number, type, 
-                                       nb_lines, nb_elements_per_line, 
-                                       elements_names)
+            if (create or clone) :
+                column = OBIDMS_column_char_writable(dms_name, column_name, 
+                                                     create, clone, clone_data, 
+                                                     version_number, type, 
+                                                     nb_lines, nb_elements_per_line, 
+                                                     elements_names)
+            else :
+                 column = OBIDMS_column_char_read(dms_name, column_name, 
+                                                  create, clone, clone_data, 
+                                                  version_number, type, 
+                                                  nb_lines, nb_elements_per_line, 
+                                                  elements_names)
         
         else :
             "Problem with the data type"
diff --git a/python/obitools3/obidms/obidmscolumn/obidmscolumn_bool/capidmscolumn_bool.pyx b/python/obitools3/obidms/obidmscolumn/obidmscolumn_bool/capidmscolumn_bool.pyx
index b0f99db..f38b903 100644
--- a/python/obitools3/obidms/obidmscolumn/obidmscolumn_bool/capidmscolumn_bool.pyx
+++ b/python/obitools3/obidms/obidmscolumn/obidmscolumn_bool/capidmscolumn_bool.pyx
@@ -4,11 +4,20 @@ from .capidmscolumn_bool cimport *
 
 
 cdef class OBIDMS_column_bool(OBIDMS_column) :
+
+    def get_item(self, line_nb, element_name):
+        return obi_column_get_bool_with_elt_name(self.pointer, line_nb, element_name.encode('utf-8'))
+        
+
+cdef class OBIDMS_column_bool_read(OBIDMS_column_bool) :     
+
+    def set_item(self, line_nb, element_name, value):
+        raise Exception('Column is read-only')
+                        
+        
+cdef class OBIDMS_column_bool_writable(OBIDMS_column_bool) :     
   
     def set_item(self, line_nb, element_name, value):
         return obi_column_set_bool_with_elt_name(self.pointer, line_nb, element_name.encode('utf-8'), value)
      
-    def get_item(self, line_nb, element_name):
-        return obi_column_get_bool_with_elt_name(self.pointer, line_nb, element_name.encode('utf-8'))
-        
     
\ No newline at end of file
diff --git a/python/obitools3/obidms/obidmscolumn/obidmscolumn_char/capidmscolumn_char.pyx b/python/obitools3/obidms/obidmscolumn/obidmscolumn_char/capidmscolumn_char.pyx
index 563b092..76a1cbc 100644
--- a/python/obitools3/obidms/obidmscolumn/obidmscolumn_char/capidmscolumn_char.pyx
+++ b/python/obitools3/obidms/obidmscolumn/obidmscolumn_char/capidmscolumn_char.pyx
@@ -4,11 +4,20 @@ from .capidmscolumn_char cimport *
 
 
 cdef class OBIDMS_column_char(OBIDMS_column) :
-  
+
+    def get_item(self, line_nb, element_name):
+        return (obi_column_get_char_with_elt_name(self.pointer, line_nb, element_name.encode('utf-8'))).decode(encoding='utf-8')[:1]
+
+cdef class OBIDMS_column_char_read(OBIDMS_column_char) :     
+
+    def set_item(self, line_nb, element_name, value):
+        raise Exception('Column is read-only')
+                        
+        
+cdef class OBIDMS_column_char_writable(OBIDMS_column_char) :     
+
     def set_item(self, line_nb, element_name, value):
         return obi_column_set_char_with_elt_name(self.pointer, line_nb, element_name.encode('utf-8'), value.encode('utf-8'))
      
-    def get_item(self, line_nb, element_name):
-        return (obi_column_get_char_with_elt_name(self.pointer, line_nb, element_name.encode('utf-8'))).decode(encoding='utf-8')[:1]
         
     
\ No newline at end of file
diff --git a/python/obitools3/obidms/obidmscolumn/obidmscolumn_float/capidmscolumn_float.pyx b/python/obitools3/obidms/obidmscolumn/obidmscolumn_float/capidmscolumn_float.pyx
index ced654a..b48a616 100644
--- a/python/obitools3/obidms/obidmscolumn/obidmscolumn_float/capidmscolumn_float.pyx
+++ b/python/obitools3/obidms/obidmscolumn/obidmscolumn_float/capidmscolumn_float.pyx
@@ -4,10 +4,19 @@ from .capidmscolumn_float cimport *
 
 
 cdef class OBIDMS_column_float(OBIDMS_column) :
-  
+
+    def get_item(self, line_nb, element_name):
+        return obi_column_get_float_with_elt_name(self.pointer, line_nb, element_name.encode('utf-8'))
+
+cdef class OBIDMS_column_float_read(OBIDMS_column_float) :     
+
+    def set_item(self, line_nb, element_name, value):
+        raise Exception('Column is read-only')
+                        
+        
+cdef class OBIDMS_column_float_writable(OBIDMS_column_float) :     
+
     def set_item(self, line_nb, element_name, value):
         return obi_column_set_float_with_elt_name(self.pointer, line_nb, element_name.encode('utf-8'), value)
      
-    def get_item(self, line_nb, element_name):
-        return obi_column_get_float_with_elt_name(self.pointer, line_nb, element_name.encode('utf-8'))
     
\ No newline at end of file
diff --git a/python/obitools3/obidms/obidmscolumn/obidmscolumn_idx/capidmscolumn_idx.pyx b/python/obitools3/obidms/obidmscolumn/obidmscolumn_idx/capidmscolumn_idx.pyx
index 51babcf..e93b267 100644
--- a/python/obitools3/obidms/obidmscolumn/obidmscolumn_idx/capidmscolumn_idx.pyx
+++ b/python/obitools3/obidms/obidmscolumn/obidmscolumn_idx/capidmscolumn_idx.pyx
@@ -4,10 +4,18 @@ from .capidmscolumn_idx cimport *
 
 
 cdef class OBIDMS_column_idx(OBIDMS_column) :
-  
-    def set_item(self, line_nb, element_name, value):
-        return obi_column_set_idx_with_elt_name(self.pointer, line_nb, element_name.encode('utf-8'), value)
-     
+    
     def get_item(self, line_nb, element_name):
         return obi_column_get_idx_with_elt_name(self.pointer, line_nb, element_name.encode('utf-8'))
-    
\ No newline at end of file
+    
+cdef class OBIDMS_column_idx_read(OBIDMS_column_idx) :     
+
+    def set_item(self, line_nb, element_name, value):
+        raise Exception('Column is read-only')
+                        
+        
+cdef class OBIDMS_column_idx_writable(OBIDMS_column_idx) :     
+
+    def set_item(self, line_nb, element_name, value):
+        return obi_column_set_idx_with_elt_name(self.pointer, line_nb, element_name.encode('utf-8'), value)
+     
\ No newline at end of file
diff --git a/python/obitools3/obidms/obidmscolumn/obidmscolumn_int/capidmscolumn_int.pyx b/python/obitools3/obidms/obidmscolumn/obidmscolumn_int/capidmscolumn_int.pyx
index bcb5960..447962f 100644
--- a/python/obitools3/obidms/obidmscolumn/obidmscolumn_int/capidmscolumn_int.pyx
+++ b/python/obitools3/obidms/obidmscolumn/obidmscolumn_int/capidmscolumn_int.pyx
@@ -4,11 +4,19 @@ from .capidmscolumn_int cimport *
 
 
 cdef class OBIDMS_column_int(OBIDMS_column) :
-  
-    def set_item(self, line_nb, element_name, value):
-        return obi_column_set_int_with_elt_name(self.pointer, line_nb, element_name.encode('utf-8'), value)
-     
+
     def get_item(self, line_nb, element_name):
         return obi_column_get_int_with_elt_name(self.pointer, line_nb, element_name.encode('utf-8'))
+  
+  
+cdef class OBIDMS_column_int_read(OBIDMS_column_int) :     
+
+    def set_item(self, line_nb, element_name, value):
+        raise Exception('Column is read-only')
+                        
         
-    
\ No newline at end of file
+cdef class OBIDMS_column_int_writable(OBIDMS_column_int) :     
+
+    def set_item(self, line_nb, element_name, value):
+        return obi_column_set_int_with_elt_name(self.pointer, line_nb, element_name.encode('utf-8'), value)
+ 
\ No newline at end of file