diff --git a/python/obitools3/obidms/_obidms.pxd b/python/obitools3/obidms/_obidms.pxd
index 34a40b0..92f5f29 100644
--- a/python/obitools3/obidms/_obidms.pxd
+++ b/python/obitools3/obidms/_obidms.pxd
@@ -20,7 +20,7 @@ cdef class OBIDMS:
                                     bint create=*, 
                                     bint clone=*, bint clone_data=*,
                                     obiversion_t version_number=*, 
-                                    OBIType_t data_type=*,
+                                    str type=*,
                                     index_t nb_lines=*, 
                                     index_t nb_elements_per_line=*, 
                                     list elements_names=*,
diff --git a/python/obitools3/obidms/_obidms.pyx b/python/obitools3/obidms/_obidms.pyx
index ae35f80..6e0b71e 100644
--- a/python/obitools3/obidms/_obidms.pyx
+++ b/python/obitools3/obidms/_obidms.pyx
@@ -16,6 +16,13 @@ from .capi.obidmscolumn cimport obi_column_get_header_from_name, \
                                 obi_column_format_date, \
                                 OBIDMS_column_header_p
 from .capi.obitypes cimport const_char_p, \
+                            OBIType_t, \
+                            OBI_INT, \
+                            OBI_FLOAT, \
+                            OBI_BOOL, \
+                            OBI_CHAR, \
+                            OBI_STR, \
+                            OBI_SEQ, \
                             name_data_type
                             
 
@@ -121,7 +128,7 @@ cdef class OBIDMS :
                                     bint create=False, 
                                     bint clone=False, bint clone_data=True,
                                     obiversion_t version_number=-1, 
-                                    OBIType_t data_type= <OBIType_t> 0,
+                                    str type='',
                                     index_t nb_lines=0, 
                                     index_t nb_elements_per_line=0, 
                                     list elements_names=None,
@@ -133,7 +140,8 @@ cdef class OBIDMS :
         cdef object subclass        # TODO object?
         cdef bytes column_name_b
         cdef OBIDMS_column_header_p header
-        
+        cdef OBIType_t data_type
+                
         header = NULL
         
         # Format the character string to send to C function
@@ -141,15 +149,30 @@ cdef class OBIDMS :
         
         # Get the header of the latest version of the column if 
         # some needed informations are not provided
-        if ((not data_type or not nb_elements_per_line) and not create) :
+        if ((not type or not nb_elements_per_line) and not create) :
             header = obi_column_get_header_from_name(self.pointer, column_name_b, version_number)
             
         # Get the data type if not provided
-        if not data_type :
+        if not type :
             if create :
                 raise Exception("A data type must be specified")
             else :
                 data_type = header.data_type
+        else :
+            if type == 'OBI_INT' :
+                data_type = OBI_INT
+            elif type == 'OBI_FLOAT' :
+                data_type = OBI_FLOAT
+            elif type == 'OBI_BOOL' :
+                data_type = OBI_BOOL
+            elif type == 'OBI_CHAR' :
+                data_type = OBI_CHAR
+            elif type == 'OBI_STR' :
+                data_type = OBI_STR
+            elif type == 'OBI_SEQ' :
+                data_type = OBI_SEQ
+            else :
+                raise Exception("Invalid provided data type")
 
         # Get the number of elements per line if not provided and needed
         if not nb_elements_per_line :
@@ -165,7 +188,7 @@ cdef class OBIDMS :
         
         # Open the column with the right subclass depending on the data type, the mode 
         # (read-only or writable) and whether there are multiple elements per line or not  
-        if data_type == 1 :
+        if data_type == OBI_INT :
             if (create or clone) :
                 if nb_elements_per_line == 1 :
                     subclass = OBIDMS_column_int_writable
@@ -176,7 +199,7 @@ cdef class OBIDMS :
                     subclass = OBIDMS_column_int
                 else :
                     subclass = OBIDMS_column_int_multi_elts
-        elif data_type == 2 :
+        elif data_type == OBI_FLOAT :
             if (create or clone) :
                 if nb_elements_per_line == 1 :
                     subclass = OBIDMS_column_float_writable
@@ -187,7 +210,7 @@ cdef class OBIDMS :
                     subclass = OBIDMS_column_float
                 else :
                     subclass = OBIDMS_column_float_multi_elts
-        elif data_type == 3 :
+        elif data_type == OBI_BOOL :
             if (create or clone) :
                 if nb_elements_per_line == 1 :
                     subclass = OBIDMS_column_bool_writable
@@ -198,7 +221,7 @@ cdef class OBIDMS :
                     subclass = OBIDMS_column_bool
                 else :
                     subclass = OBIDMS_column_bool_multi_elts
-        elif data_type == 4 :
+        elif data_type == OBI_CHAR :
             if (create or clone) :
                 if nb_elements_per_line == 1 :
                     subclass = OBIDMS_column_char_writable
@@ -209,7 +232,7 @@ cdef class OBIDMS :
                     subclass = OBIDMS_column_char
                 else :
                     subclass = OBIDMS_column_char_multi_elts
-        elif data_type == 5 :
+        elif data_type == OBI_STR :
             if (create or clone) :
                 if nb_elements_per_line == 1 :
                     subclass = OBIDMS_column_str_writable
@@ -220,7 +243,7 @@ cdef class OBIDMS :
                     subclass = OBIDMS_column_str
                 else :
                     subclass = OBIDMS_column_str_multi_elts
-        elif data_type == 6 :
+        elif data_type == OBI_SEQ :
             if (create or clone) :
                 if nb_elements_per_line == 1 :
                     subclass = OBIDMS_column_seq_writable
@@ -254,7 +277,7 @@ cdef class OBIDMS_column :
                  bint create, 
                  bint clone, bint clone_data,
                  obiversion_t version_number, 
-                 OBIType_t type,    # There's a problem with this with the OBI_IDX columns as there are 2 subtypes
+                 OBIType_t type,
                  index_t nb_lines, 
                  index_t nb_elements_per_line, 
                  list elements_names,
@@ -267,7 +290,7 @@ cdef class OBIDMS_column :
         cdef bytes array_name_b
         cdef bytes elements_names_b
         cdef bytes comments_b
-        
+       
         # Fill structure
         self.dms = dms
         self.data_type = bytes2str(name_data_type(type))
diff --git a/python/obitools3/obidms/capi/obitypes.pxd b/python/obitools3/obidms/capi/obitypes.pxd
index dae404c..374c7ee 100644
--- a/python/obitools3/obidms/capi/obitypes.pxd
+++ b/python/obitools3/obidms/capi/obitypes.pxd
@@ -17,7 +17,14 @@ cdef extern from "obidmscolumn.h" nogil:
 cdef extern from "obitypes.h" nogil:
 
     enum OBIType:
-        pass
+        OBI_VOID,
+        OBI_INT,
+        OBI_FLOAT,
+        OBI_BOOL,
+        OBI_CHAR,
+        OBI_STR,
+        OBI_SEQ
+
     
     ctypedef OBIType OBIType_t