diff --git a/src/C/H5Fed_retrieve.c b/src/C/H5Fed_retrieve.c
index 08bf376..89f45d5 100644
--- a/src/C/H5Fed_retrieve.c
+++ b/src/C/H5Fed_retrieve.c
@@ -38,7 +38,7 @@ H5FedBeginTraverseEntities (
 	) {
 	h5t_iterator_t* iter;
 	H5_ENTER_API (f, __func__);
-	if (h5t_create_mesh_iterator (f, &iter, codim) < 0) {
+	if (h5t_create_leaf_iterator (f, &iter, codim) < 0) {
 		return (void*)H5_ERR;
 	}
 	return iter;
@@ -143,16 +143,6 @@ H5FedGetVertexIndicesOfTriangle (
 	return h5t_get_vertex_indices_of_triangle (f, entity_id, vertex_indices);
 }
 
-h5_err_t
-H5FedGetVertexIndicesOfTriangleCClockwise (
-	h5_file_t* const f,
-	h5_id_t entity_id,
-	h5_id_t* vertex_indices
-	) {
-	H5_ENTER_API (f, __func__);
-	return h5t_get_vertex_indices_of_triangle_cclockwise (f, entity_id, vertex_indices);
-}
-
 h5_err_t
 H5FedGetVertexIndicesOfTet (
 	h5_file_t* const f,
diff --git a/src/h5core/h5_core_private.h b/src/h5core/h5_core_private.h
index eeb62e3..7f46180 100644
--- a/src/h5core/h5_core_private.h
+++ b/src/h5core/h5_core_private.h
@@ -42,8 +42,6 @@
 	if ((int64_t)(ptrdiff_t)(func) <= (int64_t)H5_ERR)	\
 		return H5_ERR;
 
-#define UNUSED_ARGUMENT(x) (void)x
-
 #ifdef IPL_XT3
 # define SEEK_END 2 
 #endif
diff --git a/src/h5core/h5t_core_private.h b/src/h5core/h5t_core_private.h
index d2221fa..617835b 100644
--- a/src/h5core/h5t_core_private.h
+++ b/src/h5core/h5t_core_private.h
@@ -88,8 +88,7 @@
 #define h5tpriv_build_triangle_id( face_idx, elem_idx )	 \
 	( h5tpriv_build_entity_id ( H5T_TYPE_TRIANGLE, face_idx, elem_idx ) )
 
-#define h5tpriv_build_elem_id( elem_idx )				\
-	( h5tpriv_build_entity_id ( f->t->mesh_type, 0, elem_idx ) )
+
 
 #define h5tpriv_get_face_idx( entity_id )				\
 	( (entity_id & H5T_FACE_MASK) >> (sizeof(h5_id_t)*7) )
diff --git a/src/h5core/h5t_map.c b/src/h5core/h5t_map.c
index 071e7e0..8afd7ef 100644
--- a/src/h5core/h5t_map.c
+++ b/src/h5core/h5t_map.c
@@ -290,22 +290,6 @@ h5t_get_vertex_indices_of_triangle (
 		f, face_idx, elem_idx, vertex_indices);
 }
 
-h5_err_t
-h5t_get_vertex_indices_of_triangle_cclockwise (
-	h5_file_t* const f,
-	const h5_loc_id_t entity_id,
-	h5_loc_idx_t* vertex_indices
-	) {
-	TRY( h5t_get_vertex_indices_of_triangle (f, entity_id, vertex_indices) );
-	h5_float64_t P0[3];
-	h5_float64_t P1[3];
-	h5_float64_t P2[3];
-	TRY( h5t_get_vertex_coords_by_index (f, vertex_indices[0], P0) );
-	TRY( h5t_get_vertex_coords_by_index (f, vertex_indices[1], P1) );
-	TRY( h5t_get_vertex_coords_by_index (f, vertex_indices[2], P2) );
-
-}
-
 h5_err_t
 h5t_get_vertex_indices_of_triangle2 (
 	h5_file_t* const f,
diff --git a/src/h5core/h5t_retrieve.c b/src/h5core/h5t_retrieve.c
index d84c2d6..8b99843 100644
--- a/src/h5core/h5t_retrieve.c
+++ b/src/h5core/h5t_retrieve.c
@@ -7,45 +7,51 @@
   Skip elements which have been refined on a level <= the current one.
 */
 static h5_err_t
-skip_to_next_elem_on_level (
+iter_leaf_elem_idx (
 	h5_file_t* f,
-	h5t_mesh_iterator_t* iter
+	h5t_leaf_iterator_t* iter
 	) {
 	h5_generic_loc_elem_t* el;
 	do {
 		iter->elem_idx++;
-		if (iter->elem_idx >= f->t->num_elems[iter->level_idx]) {
+		if (iter->elem_idx >= f->t->num_elems[iter->leaf_level]) {
 			return H5_NOK;
 		}
 		el = h5tpriv_get_loc_elem (f, iter->elem_idx);
-	} while (h5tpriv_elem_is_on_level (f, el, iter->level_idx) == H5_NOK);
+	} while (h5tpriv_elem_is_on_level (f, el, iter->leaf_level) == H5_NOK);
 	return H5_SUCCESS;
 }
 
 static h5_loc_id_t
-iterate_elems (
+iterate_leaf_elems (
 	h5_file_t* const f,
-	h5t_mesh_iterator_t* iter
+	union h5t_iterator* iter
 	) {
-	if ( skip_to_next_elem_on_level (f, iter) == H5_NOK) {
+	h5t_leaf_iterator_t* it = (h5t_leaf_iterator_t*)&iter->leaf;
+	if ( iter_leaf_elem_idx (f, it) == H5_NOK) {
 		h5_debug ( f, "Traversing done!" );
 		return H5_NOK;
 	}
-	return h5tpriv_build_elem_id ( iter->elem_idx );
+	int dim = it->ref_elem->dim;
+	h5_loc_id_t type_id = it->ref_elem->entity_types[dim];
+	return h5tpriv_build_entity_id (type_id, 0, it->elem_idx );
 }
 
 static h5_loc_id_t
 iterate_boundary_elems (
 	h5_file_t* const f,
-	h5t_mesh_iterator_t* iter
+	h5t_iterator_t* iter
 	) {
+	h5t_leaf_iterator_t* it = (h5t_leaf_iterator_t*)&iter->leaf;
 	do {
-		if ( skip_to_next_elem_on_level (f, iter) == H5_NOK) {
+		if ( iter_leaf_elem_idx (f, it) == H5_NOK) {
 			h5_debug ( f, "Traversing done!" );
 			return H5_NOK;
 		}
-	} while (!h5tpriv_is_boundary_elem (f, iter->elem_idx));
-	return h5tpriv_build_elem_id ( iter->elem_idx );
+	} while (!h5tpriv_is_boundary_elem (f, it->elem_idx));
+	int dim = it->ref_elem->dim;
+	h5_loc_id_t type_id = it->ref_elem->entity_types[dim];
+	return h5tpriv_build_entity_id (type_id, 0, it->elem_idx );
 }
 
 
@@ -56,54 +62,56 @@ iterate_boundary_elems (
 static h5_loc_id_t
 iterate_boundary_facets (
 	h5_file_t* const f,
-	h5t_mesh_iterator_t* iter
+	h5t_iterator_t* iter
 	) {
-	int num_facets = h5tpriv_ref_elem_get_num_facets (iter) - 1;
-	int dim = h5tpriv_ref_elem_get_dim (iter) - iter->codim;
+	h5t_leaf_iterator_t* it = (h5t_leaf_iterator_t*)&iter->leaf;
+	int num_facets = h5tpriv_ref_elem_get_num_facets (it) - 1;
+	int dim = h5tpriv_ref_elem_get_dim (it) - it->codim;
 	do {
-		if (iter->face_idx >= num_facets) {
+		if (it->face_idx >= num_facets) {
 			h5_loc_id_t elem_id;
 			TRY( elem_id = iterate_boundary_elems (f, iter) );
 			if (elem_id == H5_NOK) {
 				return H5_NOK;	// done!
 			}
-			iter->elem_idx = h5tpriv_get_elem_idx (elem_id);
-			iter->face_idx = 0;
+			it->elem_idx = h5tpriv_get_elem_idx (elem_id);
+			it->face_idx = 0;
 		} else {
-			iter->face_idx++;
+			it->face_idx++;
 		}
-	} while (! h5tpriv_is_boundary_facet (f, iter->elem_idx, iter->face_idx));
-	int type = h5tpriv_ref_elem_get_entity_type (iter->ref_elem, dim);
-	return h5tpriv_build_entity_id (type, iter->face_idx, iter->elem_idx );
+	} while (! h5tpriv_is_boundary_facet (f, it->elem_idx, it->face_idx));
+	int type = h5tpriv_ref_elem_get_entity_type (it->ref_elem, dim);
+	return h5tpriv_build_entity_id (type, it->face_idx, it->elem_idx );
 }
 
 /*!
   Travere entities with co-dim > 0
 */
 static h5_loc_id_t
-iterate_faces (
+iterate_leaf_faces (
 	h5_file_t* const f,
-	h5t_mesh_iterator_t* iter
+	h5t_iterator_t* iter
 	) {
+	h5t_leaf_iterator_t* it = (h5t_leaf_iterator_t*)iter;
 	h5_idlist_t* entry;
-	int dim = h5tpriv_ref_elem_get_dim (iter) - iter->codim;
-	int num_faces = h5tpriv_ref_elem_get_num_faces (iter, dim) - 1;
+	int dim = h5tpriv_ref_elem_get_dim (it) - it->codim;
+	int num_faces = h5tpriv_ref_elem_get_num_faces (it, dim) - 1;
 	int i = -1;
 	do {
-		if (iter->face_idx >= num_faces) {
-			if (skip_to_next_elem_on_level (f, iter) == H5_NOK) {
+		if (it->face_idx >= num_faces) {
+			if (iter_leaf_elem_idx (f, it) == H5_NOK) {
 				h5_debug (f, "Traversing done!");
 				return H5_NOK;
 			}
-			iter->face_idx = 0;
+			it->face_idx = 0;
 		} else {
-			iter->face_idx++;
+			it->face_idx++;
 		}
 		// Skip already visited faces:
 
 		//  1. Get list of all elements with this face. Actually we
 		//     retrieve a list of entities sorted by the element index.
-		TRY( (iter->find)(f, iter->face_idx, iter->elem_idx, &entry) );
+		TRY( (it->find)(f, it->face_idx, it->elem_idx, &entry) );
 
 		// 2. Go to first element in list which is on current level
 		i = -1;
@@ -112,13 +120,13 @@ iterate_faces (
 			i++;
 			h5_loc_idx_t idx = h5tpriv_get_elem_idx (entry->items[i]);
 			el = h5tpriv_get_loc_elem (f, idx);
-		} while (h5tpriv_elem_is_on_level (f, el, iter->level_idx) == H5_NOK);
+		} while (h5tpriv_elem_is_on_level (f, el, it->leaf_level) == H5_NOK);
 
 		// 3. Face already visited if 
-	} while (iter->elem_idx > h5tpriv_get_elem_idx(entry->items[i]));
+	} while (it->elem_idx > h5tpriv_get_elem_idx(entry->items[i]));
 	/*
-	  note: in above test iter->elem_idx is always greater or equal to the
-	  compared index. It cannot be smaller since iter->elem_idx is on the
+	  note: in above test it->elem_idx is always greater or equal to the
+	  compared index. It cannot be smaller since it->elem_idx is on the
 	  current level and the element index of entry->items[i] is the smallest
 	  element index with the given face on the current level.
 	*/
@@ -131,28 +139,29 @@ iterate_faces (
 static h5_loc_id_t
 iterate_boundary_faces (
 	h5_file_t* const f,
-	h5t_mesh_iterator_t* iter
+	h5t_iterator_t* iter
 	) {
+	h5t_leaf_iterator_t* it = (h5t_leaf_iterator_t*)iter;
 	// TODO!!!
-	int dim = h5tpriv_ref_elem_get_dim (iter) - iter->codim;
-	int num_faces = h5tpriv_ref_elem_get_num_faces (iter, dim) - 1;
+	int dim = h5tpriv_ref_elem_get_dim (it) - it->codim;
+	int num_faces = h5tpriv_ref_elem_get_num_faces (it, dim) - 1;
 	do {
 		// iterate to next boundary face
 		do {
 			// first iterate over all faces of element, if done
 			// goto next element
-			if (iter->face_idx >= num_faces) {
+			if (it->face_idx >= num_faces) {
 				h5_loc_id_t elem_id;
 				TRY( elem_id = iterate_boundary_elems (f, iter) );
 				if (elem_id == H5_NOK) {
 					return H5_NOK;	// done!
 				}
-				iter->face_idx = 0;
+				it->face_idx = 0;
 			} else {
-				iter->face_idx++;
+				it->face_idx++;
 			}
 		} while (! h5tpriv_is_boundary_face (
-				 f, dim, iter->elem_idx, iter->face_idx));
+				 f, dim, it->elem_idx, it->face_idx));
 		// Skip already visited faces
 	} while (0);
 	return h5_error_internal (f, __FILE__, __func__, __LINE__);
@@ -161,7 +170,7 @@ iterate_boundary_faces (
 static h5_loc_id_t
 iterate_tags (
 	h5_file_t* const f,
-	h5t_tag_iterator_t* iter
+	h5t_iterator_t* iter
 	) {
 	UNUSED_ARGUMENT (f);
 #if 0
@@ -180,35 +189,35 @@ iterate_tags (
 }
 
 h5_err_t
-h5t_init_mesh_iterator (
+h5t_init_leaf_iterator (
 	h5_file_t* f,
 	h5t_iterator_t* iter,
 	int codim
 	) {
-	h5t_mesh_iterator_t* it = (h5t_mesh_iterator_t*)iter;
+	h5t_leaf_iterator_t* it = (h5t_leaf_iterator_t*)&iter->leaf;
 	it->face_idx = 999;
 	it->elem_idx = -1;
 	it->codim = codim;
-	it->level_idx = f->t->cur_level;
+	it->leaf_level = f->t->cur_level;
 	it->ref_elem = f->t->ref_elem;
 
 	if (it->codim > 0) {
-		it->iter = iterate_faces;
+		it->iter = iterate_leaf_faces;
 	} else if (it->codim == 0) {
-		it->iter = iterate_elems;
+		it->iter = iterate_leaf_elems;
 	}
 	return H5_SUCCESS;
 }
 
 h5_err_t
-h5t_create_mesh_iterator (
+h5t_create_leaf_iterator (
 	h5_file_t* f,
 	h5t_iterator_t** iter,
 	int codim
 	) {
-	h5t_mesh_iterator_t* it;
-	TRY( it = h5priv_calloc (f, 1, sizeof (h5t_mesh_iterator_t)) );
-	TRY( h5t_init_mesh_iterator (f, (h5t_iterator_t*)it, codim) );
+	h5t_leaf_iterator_t* it;
+	TRY( it = h5priv_calloc (f, 1, sizeof (h5t_leaf_iterator_t)) );
+	TRY( h5t_init_leaf_iterator (f, (h5t_iterator_t*)it, codim) );
 	*iter =  (h5t_iterator_t*)it;
 	return H5_SUCCESS;
 }
@@ -219,12 +228,12 @@ h5t_create_boundary_face_iterator (
 	h5t_iterator_t** iter,
 	int codim
 	) {
-	h5t_mesh_iterator_t* it;
-	TRY( it = h5priv_calloc (f, 1, sizeof (h5t_mesh_iterator_t)) );
+	h5t_leaf_iterator_t* it;
+	TRY( it = h5priv_calloc (f, 1, sizeof (h5t_leaf_iterator_t)) );
 	it->face_idx = 999; // just a high enough number
 	it->elem_idx = -1;
 	it->codim = codim;
-	it->level_idx = f->t->cur_level;
+	it->leaf_level = f->t->cur_level;
 	it->ref_elem = f->t->ref_elem;
 
 	if (it->codim <= 0 || it->codim > it->ref_elem->dim) {
@@ -246,7 +255,7 @@ h5t_create_mtag_iterator (
 	const char* name
 	) {
 	h5t_tag_iterator_t* it;
-	TRY( it = h5priv_calloc (f, 1, sizeof (h5t_tag_iterator_t)) );
+	TRY( it = h5priv_calloc (f, 1, sizeof (*it)) );
 	h5t_open_mtagset (f, name, &it->tagset);
 	it->elem_idx = -1;
 	it->subentity_idx = 999;
@@ -269,7 +278,8 @@ h5t_iterate_entities (
 	h5_file_t* const f,
 	h5t_iterator_t* iter
 	) {
-	return (iter->iter (f, iter));
+	h5t_generic_iterator_t* it = (h5t_generic_iterator_t*)iter;
+	return (it->iter (f, iter));
 }
 		   
 h5_err_t
@@ -278,13 +288,11 @@ h5t_end_iterate_entities (
 	h5t_iterator_t* iter
 	) {
 	UNUSED_ARGUMENT (f);
-	h5t_mesh_iterator_t* it = (h5t_mesh_iterator_t*)iter;
+	bzero (iter, sizeof(*iter));
+	h5t_leaf_iterator_t* it = (h5t_leaf_iterator_t*)&iter->leaf;
 	it->face_idx = -1;
 	it->elem_idx = -1;
 	it->codim = -1;
-	it->ref_elem = NULL;
-	it->find = NULL;
-	it->iter = NULL;
 	return H5_SUCCESS;
 }
 
diff --git a/src/h5core/h5t_retrieve_private.h b/src/h5core/h5t_retrieve_private.h
index 9b1908a..0aafc9f 100644
--- a/src/h5core/h5t_retrieve_private.h
+++ b/src/h5core/h5t_retrieve_private.h
@@ -3,53 +3,6 @@
 
 #include <assert.h>
 
-/*
-  TODO: define as union of iterator types
- */
-struct h5t_iterator {
-	h5_loc_id_t (*iter)(
-		h5_file_t *const f,
-		struct h5t_iterator* iter);
-/*		 
-	const h5t_ref_elem_t* ref_elem; // pointer to reference element
-
- 	h5_id_t elem_idx;	// local element id
-	h5_id_t	face_idx;	// face id according reference element
-	int codim;		// dimension of entities to traverse
-	h5_err_t (*find)(
-		h5_file_t *const f,
-		h5_id_t face_idx,
-		h5_id_t elem_idx,
-		h5_idlist_t **retval);
-
-*/};
-
-typedef struct h5t_mesh_iterator {
-	h5_loc_id_t (*iter)(
-		h5_file_t *const f,
-		struct h5t_mesh_iterator* iter);
-	h5t_lvl_idx_t level_idx;
-	const h5t_ref_elem_t* ref_elem;
-	h5_loc_idx_t elem_idx;
-	h5_loc_idx_t face_idx;	// face id according reference element
-	int codim;		// dimension of entities to traverse
-	h5_err_t (*find)(
-		h5_file_t *const f,
-		h5_id_t face_idx,
-		h5_id_t elem_idx,
-		h5_idlist_t **retval);
-} h5t_mesh_iterator_t;
-
-typedef struct h5t_tag_iterator {
-	h5_loc_id_t (*iter)(
-		h5_file_t *const f,
-		struct h5t_tag_iterator* iter);
-	h5t_lvl_idx_t level_idx;
-	h5t_tagset_t* tagset;
-	h5_loc_idx_t elem_idx;
-	int subentity_idx;
-} h5t_tag_iterator_t;
-
 /*
 h5_err_t
 h5tpriv_elem_is_on_cur_level (
@@ -59,7 +12,7 @@ h5tpriv_elem_is_on_cur_level (
 */
 struct h5t_retrieve_methods {
 	h5_err_t (*init_entity_iterator)(
-		h5_file_t* const, h5t_mesh_iterator_t*, const int);
+		h5_file_t* const, h5t_iterator_t*, const int);
 };
 
 extern struct h5t_retrieve_methods h5tpriv_trim_retrieve_methods;
@@ -100,7 +53,7 @@ h5tpriv_elem_is_on_level (
 static inline h5_err_t
 h5tpriv_init_entity_iterator (
 	h5_file_t* f,
-	h5t_mesh_iterator_t* const iter,
+	h5t_iterator_t* const iter,
 	const int codim
 	) {
 	return (*f->t->methods.retrieve->init_entity_iterator) (f, iter, codim);
diff --git a/src/h5core/h5t_retrieve_tetm.c b/src/h5core/h5t_retrieve_tetm.c
index 697b558..aed1106 100644
--- a/src/h5core/h5t_retrieve_tetm.c
+++ b/src/h5core/h5t_retrieve_tetm.c
@@ -6,21 +6,22 @@
 static h5_err_t
 begin_iterate_entities (
 	h5_file_t* f,
-	h5t_mesh_iterator_t* const iter,
+	h5t_iterator_t* const iter,
 	const int codim
 	) {
-	switch (iter->ref_elem->dim - codim) {
+	h5t_leaf_iterator_t* it = (h5t_leaf_iterator_t*)&iter->leaf;
+	switch (it->ref_elem->dim - codim) {
 	case 0: // iterate vertices
-		iter->find = h5tpriv_find_tv2;
+		it->find = h5tpriv_find_tv2;
 		break;
 	case 1: // iterate edges
-		iter->find = h5tpriv_find_te2;
+		it->find = h5tpriv_find_te2;
 		break;
 	case 2: // iterate faces
-		iter->find = h5tpriv_find_td2;
+		it->find = h5tpriv_find_td2;
 		break;
 	case 3: // iterate elems
-		iter->find = NULL;
+		it->find = NULL;
 		break;
 	default:
 		return h5_error_internal (f, __FILE__, __func__, __LINE__);
diff --git a/src/h5core/h5t_retrieve_trim.c b/src/h5core/h5t_retrieve_trim.c
index 44fb4aa..29470ff 100644
--- a/src/h5core/h5t_retrieve_trim.c
+++ b/src/h5core/h5t_retrieve_trim.c
@@ -6,18 +6,19 @@
 static h5_err_t
 begin_iterate_entities (
 	h5_file_t* f,
-	h5t_mesh_iterator_t* iter,
+	h5t_iterator_t* iter,
 	const int codim
 	) {
-	switch (h5tpriv_ref_elem_get_dim (iter) - codim) {
+	h5t_leaf_iterator_t* it = (h5t_leaf_iterator_t*)&iter->leaf;
+	switch (h5tpriv_ref_elem_get_dim (it) - codim) {
 	case 0: // iterate vertices
-		iter->find = h5tpriv_find_tv2;
+		it->find = h5tpriv_find_tv2;
 		break;
 	case 1: // iterate edges
-		iter->find = h5tpriv_find_te2;
+		it->find = h5tpriv_find_te2;
 		break;
 	case 2: // iterate elems
-		iter->find = NULL;
+		it->find = NULL;
 		break;
 	default:
 		return h5_error_internal (f, __FILE__, __func__, __LINE__);
diff --git a/src/h5core/h5t_store.c b/src/h5core/h5t_store.c
index d2a2e42..59067a5 100644
--- a/src/h5core/h5t_store.c
+++ b/src/h5core/h5t_store.c
@@ -464,10 +464,10 @@ h5t_create_index_set (
 
 	for (codim = 0; codim <= dim; codim++) {
 		h5_glb_idx_t idx = 0;
-		h5t_mesh_iterator_t it;
+		h5t_leaf_iterator_t it;
 		h5_glb_id_t entity_id;
-		TRY( h5t_init_mesh_iterator (f, (h5t_iterator_t*)&it, codim) );
-		while ((entity_id = it.iter(f,&it)) >= 0) {
+		TRY( h5t_init_leaf_iterator (f, (h5t_iterator_t*)&it, codim) );
+		while ((entity_id = it.iter(f, (h5t_iterator_t*)&it)) >= 0) {
 			TRY( h5t_set_mtag_by_name (f, "__IndexSet__", entity_id, 1, &idx) );
 		}
 	}
diff --git a/src/include/h5core/h5_core.h b/src/include/h5core/h5_core.h
index 691575a..477a016 100644
--- a/src/include/h5core/h5_core.h
+++ b/src/include/h5core/h5_core.h
@@ -1,6 +1,8 @@
 #ifndef __H5_CORE_H
 #define __H5_CORE_H
 
+#define UNUSED_ARGUMENT(x) (void)x
+
 #include "h5_types.h"
 #include "h5_errno.h"
 
diff --git a/src/include/h5core/h5t_map.h b/src/include/h5core/h5t_map.h
index b0fc2aa..6746a04 100644
--- a/src/include/h5core/h5t_map.h
+++ b/src/include/h5core/h5t_map.h
@@ -66,13 +66,6 @@ h5t_get_vertex_indices_of_triangle (
 	h5_loc_idx_t* vertex_indices
 	);
 
-h5_err_t
-h5t_get_vertex_indices_of_triangle_cclockwise (
-	h5_file_t* const f,
-	const h5_loc_id_t entity_id,
-	h5_loc_idx_t* vertex_indices
-	);
-
 h5_err_t
 h5t_get_vertex_indices_of_triangle2 (
 	h5_file_t* const f,
diff --git a/src/include/h5core/h5t_retrieve.h b/src/include/h5core/h5t_retrieve.h
index 354408c..45a9f85 100644
--- a/src/include/h5core/h5t_retrieve.h
+++ b/src/include/h5core/h5t_retrieve.h
@@ -1,17 +1,60 @@
 #ifndef __H5T_RETRIEVE_H
 #define __H5T_RETRIEVE_H
 
-typedef struct h5t_iterator h5t_iterator_t;
+struct h5t_tagset;
+union h5t_iterator;
+
+typedef struct {
+	h5_loc_id_t (*iter)(h5_file_t *const f, union h5t_iterator* iter);
+	h5t_lvl_idx_t leaf_level;
+	const h5t_ref_elem_t* ref_elem;
+	h5_loc_idx_t elem_idx;
+	h5_loc_idx_t face_idx;	// face according reference element
+	int codim;		// dimension of entities to traverse
+	h5_err_t (*find)(h5_file_t *const f, h5_id_t face_idx,
+			 h5_id_t elem_idx, h5_idlist_t **retval);
+} h5t_leaf_iterator_t;
+
+typedef struct {
+	h5_loc_id_t (*iter)(h5_file_t *const f, union h5t_iterator* iter);
+	h5t_lvl_idx_t refinement_level;
+	const h5t_ref_elem_t* ref_elem;
+	h5_loc_idx_t elem_idx;
+	h5_loc_idx_t face_idx;	// face  according reference element
+	int codim;		// dimension of entities to traverse
+	h5_err_t (*find)(h5_file_t *const f, h5_id_t face_idx,
+			 h5_id_t elem_idx, h5_idlist_t **retval);
+} h5t_level_iterator_t;
+
+typedef struct {
+	h5_loc_id_t (*iter)(h5_file_t *const f, union h5t_iterator* iter);
+	h5t_lvl_idx_t level_idx;
+	struct h5t_tagset* tagset;
+	h5_loc_idx_t elem_idx;
+	int subentity_idx;
+} h5t_tag_iterator_t;
+
+typedef struct h5t_generic_iterator {
+	h5_loc_id_t (*iter)(h5_file_t *const f, union h5t_iterator* iter);
+} h5t_generic_iterator_t;
+
+typedef union h5t_iterator {
+	h5t_leaf_iterator_t	leaf;
+	h5t_level_iterator_t	level;
+	h5t_tag_iterator_t	tag;
+	h5t_generic_iterator_t	generic;
+} h5t_iterator_t;
+
 
 h5_err_t
-h5t_init_mesh_iterator (
+h5t_init_leaf_iterator (
 	h5_file_t* f,
 	h5t_iterator_t* iter,
 	const int codim
 	);
 
 h5_err_t
-h5t_create_mesh_iterator (
+h5t_create_leaf_iterator (
 	h5_file_t* f,
 	h5t_iterator_t** iter,
 	const int codim