diff --git a/src/h5core/Makefile.am b/src/h5core/Makefile.am
index da8fff8..af60f1d 100644
--- a/src/h5core/Makefile.am
+++ b/src/h5core/Makefile.am
@@ -49,7 +49,6 @@ EXTRA_HEADERS =					\
 	h5t_core_private.h			\
 	h5t_errorhandling_private.h		\
 	h5t_hsearch_private.h			\
-	h5t_inquiry_private.h			\
 	h5t_map_private.h			\
 	h5t_openclose_private.h			\
 	h5t_readwrite_private.h			\
diff --git a/src/h5core/h5_hdf5.c b/src/h5core/h5_hdf5.c
index 5ae0059..106f366 100644
--- a/src/h5core/h5_hdf5.c
+++ b/src/h5core/h5_hdf5.c
@@ -147,23 +147,23 @@ h5priv_get_hdf5_objname_by_idx (
 	char *name,
 	size_t size
 	) {
-	ssize_t ssize;
+	ssize_t len;
 	if (name == NULL) {
-		ssize = H5Lget_name_by_idx (loc_id, ".",
+		len = H5Lget_name_by_idx (loc_id, ".",
 					    H5_INDEX_NAME, H5_ITER_INC,
 					    idx,
 					    NULL, 0,
 					    H5P_DEFAULT);
-		if (ssize < 0) goto error;
+		if (len < 0) goto error;
 	} else {
-		ssize = H5Lget_name_by_idx (loc_id, ".",
+		len = H5Lget_name_by_idx (loc_id, ".",
 					    H5_INDEX_NAME, H5_ITER_INC,
 					    idx,
 					    name, size,
 					    H5P_DEFAULT);
-		if (ssize < 0) goto error;
+		if (len < 0) goto error;
 	}
-	return size;
+	return len;
 error:
 	return h5_error (
 		f,
diff --git a/src/h5core/h5t_adjacencies_tetm.c b/src/h5core/h5t_adjacencies_tetm.c
index 9d4e31c..42c974c 100644
--- a/src/h5core/h5t_adjacencies_tetm.c
+++ b/src/h5core/h5t_adjacencies_tetm.c
@@ -13,35 +13,88 @@
 
 #include <time.h>
 
+#include <string.h>
+
 #include "h5core/h5_core.h"
 #include "h5_core_private.h"
 
+static inline h5_err_t
+alloc_tv (
+	h5_file_t* const f,
+	const h5_loc_idx_t level_idx
+
+	) {
+	h5t_fdata_t* t = f->t;
+	h5_loc_idx_t idx = (level_idx <= 0) ? 0 : t->num_vertices[level_idx-1];
+	h5_loc_idx_t last = t->num_vertices[t->num_levels-1];
+
+	h5t_adjacencies_t* adj = &t->adjacencies;
+	adj->tv.size = last;
+	size_t size = last * sizeof(adj->tv.v[0]);
+	TRY( adj->tv.v = h5priv_alloc (f, adj->tv.v, size) );
+	size = (last-idx) * sizeof(adj->tv.v[0]);
+	memset (&adj->tv.v[idx], 0, size);
+
+	return H5_SUCCESS;
+}
+
+static inline h5_err_t
+release_tv (
+	h5_file_t* const f
+	) {
+	h5t_fdata_t* t = f->t;
+	h5t_adjacencies_t* adj = &t->adjacencies;
+	if (adj->tv.v == NULL) return H5_SUCCESS;
+
+	h5_loc_idx_t idx = 0;
+	h5_loc_idx_t last = t->num_vertices[t->num_levels-1];
+	for (; idx < last; idx++) {
+		TRY( h5priv_free_idlist_items (f, &adj->tv.v[idx]) );
+	}
+	TRY( h5priv_free (f, adj->tv.v) );
+	adj->tv.v = NULL;
+	return H5_SUCCESS;
+}
+
 /*
   compute T(V) from current level up to highest levels.
 */
 static inline h5_err_t
 compute_elems_of_vertices (
 	h5_file_t* const f,
-	const h5_id_t level_idx
+	const h5_id_t from_lvl
 	) {
+	/* expand structure */
+	TRY( alloc_tv (f, from_lvl) );
+
+	/* loop over all elements in current level */
 	h5t_fdata_t* t = f->t;
-	h5_id_t idx = (level_idx <= 0) ? 0 : t->num_elems[level_idx-1];
+	h5_loc_idx_t idx = (from_lvl <= 0) ? 0 : t->num_elems[from_lvl-1];
+	h5_loc_idx_t last = t->num_elems[t->num_levels-1];
 	h5_tet_t *el = &t->loc_elems.tets[idx];
-	h5_id_t num_elems = t->num_elems[t->num_levels-1];
-	for (;idx < num_elems; idx++, el++) {
+	for (;idx < last; idx++, el++) {
 		int face_idx;
 		int num_faces = h5tpriv_ref_elem_get_num_vertices(t);
 		for (face_idx = 0; face_idx < num_faces; face_idx++) {
 			h5_id_t vidx = el->vertex_indices[face_idx];
 			TRY( h5priv_append_to_idlist (
 				     f,
-				     &t->vertices_data[vidx].tv,
+				     &t->adjacencies.tv.v[vidx],
 				     h5tpriv_build_vertex_id (face_idx, idx)) );
 		}
 	}
 	return H5_SUCCESS;
 }
 
+static inline h5_err_t
+release_te (
+	h5_file_t* const f
+	) {
+#pragma unused f
+	// @@@ TBD @@@
+	return H5_SUCCESS;
+}
+
 /*
   Compute T(E) from current level up to highest levels.
  */
@@ -66,6 +119,15 @@ compute_elems_of_edges (
 	return H5_SUCCESS;
 }
 
+static inline h5_err_t
+release_td (
+	h5_file_t* const f
+	) {
+#pragma unused f
+	// @@@ TBD @@@
+	return H5_SUCCESS;
+}
+
 static inline h5_err_t
 compute_elems_of_triangles (
 	h5_file_t* const f,
@@ -311,41 +373,48 @@ static inline h5_err_t
 add_edge (
 	h5_file_t* const f,
 	h5_idlist_t* list,
-	h5_id_t face_idx,
-	h5_id_t eid
+	h5_loc_idx_t face_idx,
+	h5_loc_idx_t elem_idx
 	) {
 	h5_idlist_t* te;
-	TRY( h5tpriv_find_te2 (f, face_idx, eid, &te) );
+	TRY( h5tpriv_find_te2 (f, face_idx, elem_idx, &te) );
 	TRY( h5priv_search_idlist (f, list, te->items[0]) );
 	return H5_SUCCESS;
 }
 
-
+/*
+  Get upward adjacent edges to vertex given by ID.
+ */
 static inline h5_err_t
 get_edges_uadj_to_vertex (
 	h5_file_t* const f,
-	const h5_id_t vid,
+	const h5_loc_id_t id,
 	h5_idlist_t** list
 	) {
 	TRY( h5priv_alloc_idlist (f, list, 8) );
 	
-	h5t_fdata_t* t = f->t;
-	h5_idlist_t* tv = &t->vertices_data[vid].tv;
+	h5t_fdata_t* const t = f->t;
+	h5_loc_idx_t idx;
+	TRY( h5t_get_vertex_index_of_vertex (f, id, &idx) );
+	h5_idlist_t* tv = &t->adjacencies.tv.v[idx];
 	h5_size_t i;
 
-	h5_id_t* vidp = tv->items;
+	h5_id_t* vidp = tv->items;	// ptr to upward adjacent elements
 	for (i = 0; i < tv->num_items; i++, vidp++) {
-		h5_id_t eid = h5tpriv_get_elem_idx (*vidp);
-		h5_id_t face = h5tpriv_get_face_idx (*vidp);
-		h5_generic_elem_t* tet = (h5_generic_elem_t*)&t->loc_elems.tets[eid];
+		h5_loc_idx_t elem_idx = h5tpriv_get_elem_idx (*vidp);
+		h5_loc_idx_t face_idx = h5tpriv_get_face_idx (*vidp);
+		h5_generic_elem_t* tet = (h5_generic_elem_t*)&t->loc_elems.tets[elem_idx];
 
 		if (h5tpriv_elem_is_on_cur_level (f, tet) == H5_NOK ) {
 			continue;
 		}
-		int map[4][3] = { {0,2,3}, {0,1,4}, {2,1,5}, {3,4,5} };
-		TRY( add_edge (f, *list, map[face][0], eid) );
-		TRY( add_edge (f, *list, map[face][1], eid) );
-		TRY( add_edge (f, *list, map[face][2], eid) );
+		h5_loc_idx_t edge_idx;
+		edge_idx = h5tpriv_get_edge_connected_to_vertex (t->ref_elem, face_idx, 0);
+		TRY( add_edge (f, *list, edge_idx, elem_idx) );
+		edge_idx = h5tpriv_get_edge_connected_to_vertex (t->ref_elem, face_idx, 1);
+		TRY( add_edge (f, *list, edge_idx, elem_idx) );
+		edge_idx = h5tpriv_get_edge_connected_to_vertex (t->ref_elem, face_idx, 2);
+		TRY( add_edge (f, *list, edge_idx, elem_idx) );
 	}
 	return H5_SUCCESS;
 }
@@ -367,27 +436,38 @@ add_triangle (
 static inline h5_err_t
 get_triangles_uadj_to_vertex (
 	h5_file_t * const f,
-	const h5_id_t vid,
+	const h5_loc_id_t id,
 	h5_idlist_t **list
 	) {
+	/*
+	  Pre-allocate a list with 8 items. Why 8? Why not?
+	  ;-) 
+	  We should change it when we have something better.
+	 */
 	TRY ( h5priv_alloc_idlist ( f, list, 8 ) );
 	
 	h5t_fdata_t* t = f->t;
-	h5_idlist_t* tv = &t->vertices_data[vid].tv;
+	h5_loc_idx_t idx;
+	TRY( h5t_get_vertex_index_of_vertex (f, id, &idx) );
+	h5_idlist_t* tv = &t->adjacencies.tv.v[idx];
+
 	h5_size_t i;
 	h5_id_t* vidp = tv->items;
 	for (i = 0; i < tv->num_items; i++, vidp++) {
-		h5_id_t eid = h5tpriv_get_elem_idx (*vidp);
-		h5_id_t face = h5tpriv_get_face_idx (*vidp);
-		h5_generic_elem_t* tet = (h5_generic_elem_t*)&t->loc_elems.tets[eid];
+		h5_id_t elem_idx = h5tpriv_get_elem_idx (*vidp);
+		h5_id_t face_idx = h5tpriv_get_face_idx (*vidp);
+		h5_generic_elem_t* tet = (h5_generic_elem_t*)&t->loc_elems.tets[elem_idx];
 
 		if (h5tpriv_elem_is_on_cur_level (f, tet) == H5_NOK) {
 			continue;
 		}
-		int map[4][3] = { {1,2,3}, {0,2,3}, {0,1,3}, {0,1,2} };
-		TRY( add_triangle (f, *list, map[face][0], eid) );
-		TRY( add_triangle (f, *list, map[face][1], eid) );
-		TRY( add_triangle (f, *list, map[face][2], eid) );
+		h5_loc_idx_t facet_idx;
+		facet_idx = h5tpriv_get_facet_connected_to_vertex (t->ref_elem, face_idx, 0);
+		TRY( add_triangle (f, *list, facet_idx, elem_idx) );
+		facet_idx = h5tpriv_get_facet_connected_to_vertex (t->ref_elem, face_idx, 1);
+		TRY( add_triangle (f, *list, facet_idx, elem_idx) );
+		facet_idx = h5tpriv_get_facet_connected_to_vertex (t->ref_elem, face_idx, 2);
+		TRY( add_triangle (f, *list, facet_idx, elem_idx) );
 	}
 	return H5_SUCCESS;
 }
@@ -395,23 +475,27 @@ get_triangles_uadj_to_vertex (
 static inline h5_err_t
 get_tets_uadj_to_vertex (
 	h5_file_t* const f,
-	const h5_id_t vid,
+	const h5_loc_id_t id,
 	h5_idlist_t** list
 	) {
 	TRY( h5priv_alloc_idlist (f, list, 8) );
 	
 	h5t_fdata_t* t = f->t;
-	h5_idlist_t* tv = &t->vertices_data[vid].tv;
+	h5_loc_idx_t idx;
+	TRY( h5t_get_vertex_index_of_vertex (f, id, &idx) );
+	h5_idlist_t* tv = &t->adjacencies.tv.v[idx];
 	h5_size_t i;
+
 	h5_id_t* vidp = tv->items;
 	for (i = 0; i < tv->num_items; i++, vidp++) {
-		h5_id_t eid = h5tpriv_get_elem_idx (*vidp);
-		h5_generic_elem_t* tet = (h5_generic_elem_t*)&t->loc_elems.tets[eid];
+		h5_id_t elem_idx = h5tpriv_get_elem_idx (*vidp);
+		h5_generic_elem_t* tet = (h5_generic_elem_t*)&t->loc_elems.tets[elem_idx];
 
 		if (h5tpriv_elem_is_on_cur_level (f, tet) == H5_NOK) {
 			continue;
 		}
-		TRY( h5priv_search_idlist (f, *list, eid) );
+		// add to result
+		TRY( h5priv_search_idlist (f, *list, elem_idx) );
 	}
 	return H5_SUCCESS;
 }
@@ -786,8 +870,10 @@ static h5_err_t
 release_internal_structs (
 	h5_file_t * const f
 	) {
-#pragma unused f
-	/* TO BE WRITTEN @@@ */
+	TRY( release_tv (f) );
+	TRY( release_te (f) );
+	TRY( release_td (f) );
+
 	return H5_SUCCESS;
 }
 
diff --git a/src/h5core/h5t_adjacencies_trim.c b/src/h5core/h5t_adjacencies_trim.c
index cff707b..b73208c 100644
--- a/src/h5core/h5t_adjacencies_trim.c
+++ b/src/h5core/h5t_adjacencies_trim.c
@@ -12,10 +12,49 @@
 */
 
 #include <time.h>
+#include <string.h>
 
 #include "h5core/h5_core.h"
 #include "h5_core_private.h"
 
+static inline h5_err_t
+alloc_tv (
+	h5_file_t* const f,
+	const h5_loc_idx_t level_idx
+
+	) {
+	h5t_fdata_t* t = f->t;
+	h5_loc_idx_t idx = (level_idx <= 0) ? 0 : t->num_vertices[level_idx-1];
+	h5_loc_idx_t last = t->num_vertices[t->num_levels-1];
+
+	h5t_adjacencies_t* adj = &t->adjacencies;
+	adj->tv.size = last;
+	size_t size = last * sizeof(adj->tv.v[0]);
+	TRY( adj->tv.v = h5priv_alloc (f, adj->tv.v, size) );
+	size = (last-idx) * sizeof(adj->tv.v[0]);
+	memset (&adj->tv.v[idx], 0, size);
+
+	return H5_SUCCESS;
+}
+
+static inline h5_err_t
+release_tv (
+	h5_file_t* const f
+	) {
+	h5t_fdata_t* t = f->t;
+	h5t_adjacencies_t* adj = &t->adjacencies;
+	if (adj->tv.v == NULL) return H5_SUCCESS;
+
+	h5_loc_idx_t idx = 0;
+	h5_loc_idx_t last = t->num_vertices[t->num_levels-1];
+	for (; idx < last; idx++) {
+		TRY( h5priv_free_idlist_items (f, &adj->tv.v[idx]) );
+	}
+	TRY( h5priv_free (f, adj->tv.v) );
+	adj->tv.v = NULL;
+	return H5_SUCCESS;
+}
+
 /*
   compute T(V) from current level up to highest levels.
 */
@@ -24,25 +63,38 @@ compute_elems_of_vertices (
 	h5_file_t* const f,
 	const h5_id_t from_lvl
 	) {
+	/* expand structure */
+	TRY( alloc_tv (f, from_lvl) );
+
+	/* loop over all elements in current level */
 	h5t_fdata_t *t = f->t;
-	h5_id_t elem_idx = (from_lvl <= 0) ? 0 : t->num_elems[from_lvl-1];
-	h5_triangle_t *el = &t->loc_elems.tris[elem_idx];
-	h5_id_t num_elems = t->num_elems[t->num_levels-1];
-	for (;elem_idx < num_elems; elem_idx++, el++) {
+	h5_loc_idx_t idx = (from_lvl <= 0) ? 0 : t->num_elems[from_lvl-1];
+	h5_loc_idx_t last = t->num_elems[t->num_levels-1];
+	h5_triangle_t *el = &t->loc_elems.tris[idx];
+	for (;idx < last; idx++, el++) {
 		int face_idx;
 		int num_faces = h5tpriv_ref_elem_get_num_vertices (t);
 		for (face_idx = 0; face_idx < num_faces; face_idx++) {
 			h5_id_t vidx = el->vertex_indices[face_idx];
 			TRY( h5priv_append_to_idlist (
 				     f,
-				     &t->vertices_data[vidx].tv,
+				     &t->adjacencies.tv.v[vidx],
 				     h5tpriv_build_vertex_id (
-					     face_idx, elem_idx)) );
+					     face_idx, idx)) );
 		}
 	}
 	return H5_SUCCESS;
 }
 
+static inline h5_err_t
+release_te (
+	h5_file_t* const f
+	) {
+#pragma unused f
+	// @@@ TBD @@@
+	return H5_SUCCESS;
+}
+
 /*
   Compute T(E) from current level up to highest levels.
  */
@@ -181,9 +233,11 @@ get_edges_uadj_to_vertex (
 	TRY ( h5priv_alloc_idlist ( f, list, 8 ) );
 	
 	h5t_fdata_t* t = f->t;
-	h5_idlist_t* tv = &t->vertices_data[entity_id].tv;
-	h5_size_t i;
+	h5_loc_idx_t idx;
+	TRY( h5t_get_vertex_index_of_vertex (f, entity_id, &idx) );
+	h5_idlist_t* tv = &t->adjacencies.tv.v[idx];
 
+	h5_size_t i;
 	h5_id_t* vertex_idp = tv->items;
 	for ( i = 0; i < tv->num_items; i++, vertex_idp++ ) {
 		h5_id_t elem_idx = h5tpriv_get_elem_idx ( *vertex_idp );
@@ -193,15 +247,11 @@ get_edges_uadj_to_vertex (
 		if ( h5tpriv_elem_is_on_cur_level ( f, el ) == H5_NOK ) {
 			continue;
 		}
-		/*
-		  upward adjacend edges to vertices according reference element
-		 */
-		int map[3][2] = { {0,1}, // edge 0, 1 are adjacent to vertex 0
-				  {0,2}, // edge 0, 2 are adjacent to vertex 1
-				  {1,2}  // edge 1, 2 are adjacent to vertex 2
-		};
-		TRY ( add_edge ( f, *list, map[face_idx][0], elem_idx ) );
-		TRY ( add_edge ( f, *list, map[face_idx][1], elem_idx ) );
+		h5_loc_idx_t edge_idx;
+		edge_idx = h5tpriv_get_edge_connected_to_vertex (t->ref_elem, face_idx, 0);
+		TRY ( add_edge ( f, *list, edge_idx, elem_idx ) );
+		edge_idx = h5tpriv_get_edge_connected_to_vertex (t->ref_elem, face_idx, 1);
+		TRY ( add_edge ( f, *list, edge_idx, elem_idx ) );
 	}
 	return H5_SUCCESS;
 }
@@ -215,17 +265,20 @@ get_triangles_uadj_to_vertex (
 	TRY ( h5priv_alloc_idlist ( f, list, 8 ) );
 	
 	h5t_fdata_t *t = f->t;
-	h5_idlist_t *tv = &t->vertices_data[entity_id].tv;
+	h5_loc_idx_t idx;
+	TRY( h5t_get_vertex_index_of_vertex (f, entity_id, &idx) );
+	h5_idlist_t* tv = &t->adjacencies.tv.v[idx];
+
 	h5_size_t i;
-	h5_id_t *vertex_id = tv->items;
-	for ( i = 0; i < tv->num_items; i++, vertex_id++ ) {
-		h5_id_t elem_id = h5tpriv_get_elem_idx ( *vertex_id );
-		h5_generic_elem_t* el = (h5_generic_elem_t*)&t->loc_elems.tris[elem_id];
+	h5_id_t *vertex_idp = tv->items;
+	for ( i = 0; i < tv->num_items; i++, vertex_idp++ ) {
+		h5_loc_idx_t elem_idx = h5tpriv_get_elem_idx ( *vertex_idp );
+		h5_generic_elem_t* el = (h5_generic_elem_t*)&t->loc_elems.tris[elem_idx];
 
 		if ( h5tpriv_elem_is_on_cur_level ( f, el ) == H5_NOK ) {
 			continue;
 		}
-		TRY ( h5priv_search_idlist ( f, *list, elem_id ) );
+		TRY ( h5priv_search_idlist ( f, *list, elem_idx ) );
 	}
 	return H5_SUCCESS;
 }
@@ -443,8 +496,9 @@ static inline h5_err_t
 release_internal_structs (
 	h5_file_t* const f
 	) {
-#pragma unused f
-	/* TO BE WRITTEN @@@ */
+	TRY( release_tv (f) );
+	TRY( release_te (f) );
+
 	return H5_SUCCESS;
 }
 
diff --git a/src/h5core/h5t_core_private.h b/src/h5core/h5t_core_private.h
index c70581a..b042b7d 100644
--- a/src/h5core/h5t_core_private.h
+++ b/src/h5core/h5t_core_private.h
@@ -10,7 +10,6 @@
 #include "h5t_access_private.h"
 #include "h5t_adjacencies_private.h"
 #include "h5t_consts_private.h"
-#include "h5t_inquiry_private.h"
 #include "h5t_errorhandling_private.h"
 #include "h5t_hsearch_private.h"
 #include "h5t_map_private.h"
diff --git a/src/h5core/h5t_hsearch.c b/src/h5core/h5t_hsearch.c
index 976e5fc..7aabe7b 100644
--- a/src/h5core/h5t_hsearch.c
+++ b/src/h5core/h5t_hsearch.c
@@ -315,7 +315,7 @@ h5tpriv_find_tv2 (
 	) {
 
 	h5_id_t idx = h5tpriv_get_loc_elem_vertex_idx (f, elem_idx, face_idx);
-	*retval = &f->t->vertices_data[idx].tv;
+	*retval = &f->t->adjacencies.tv.v[idx];
 
 	return H5_SUCCESS;
 }
diff --git a/src/h5core/h5t_map.c b/src/h5core/h5t_map.c
index e7cc2a5..4407d3f 100644
--- a/src/h5core/h5t_map.c
+++ b/src/h5core/h5t_map.c
@@ -105,7 +105,7 @@ h5tpriv_get_local_vid (
 /*!
   compare two elems given by their local id
 */
-static int
+static inline int
 cmp_elems (
 	h5_file_t* const  f,
 	const h5_id_t elem_idx1,
@@ -129,7 +129,7 @@ cmp_elems (
 	return 0;
 }
 
-static int
+static inline int
 cmp_elems1 (
 	h5_file_t* f,
 	h5_id_t	elem_idx1,
diff --git a/src/h5core/h5t_openclose.c b/src/h5core/h5t_openclose.c
index b413450..aaa2e4c 100644
--- a/src/h5core/h5t_openclose.c
+++ b/src/h5core/h5t_openclose.c
@@ -254,7 +254,6 @@ init_fdata (
 	t->num_elems_on_level =		NULL;
 	t->map_elem_g2l.items =		NULL;
 	t->vertices =			NULL; 
-	t->vertices_data =		NULL;
 	t->num_vertices =		NULL;
 	t->map_vertex_g2l.items =	NULL;
 	t->mtags.names =		NULL;
@@ -527,8 +526,7 @@ release_vertices (
 	h5_file_t* const f
 	) {
 	h5t_fdata_t* t = f->t;
-	TRY( h5priv_free (f, t->vertices) ); 
-	TRY( h5priv_free (f, t->vertices_data) );
+	TRY( h5priv_free (f, t->vertices) );
 	TRY( h5priv_free (f, t->num_vertices) );
 	TRY( h5priv_free (f, t->map_vertex_g2l.items) );
 
@@ -579,19 +577,20 @@ h5t_set_level (
 	return H5_SUCCESS;
 }
 
+/*
+  Allocate \c num additional vertices. 
+ */
 h5_err_t
 h5tpriv_alloc_num_vertices (
 	h5_file_t* const f,
-	const h5_size_t num_vertices
+	const h5_size_t num
 	) {
 	h5t_fdata_t* t = f->t;
 
-	ssize_t size = num_vertices * sizeof (t->vertices[0]);
+	ssize_t size = num * sizeof (t->vertices[0]);
 	TRY( t->vertices = h5priv_alloc (f, t->vertices, size) );
-	size = num_vertices * sizeof (t->vertices_data[0]);
-	TRY( t->vertices_data = h5priv_alloc (f, t->vertices_data, size) );
-	TRY( h5priv_alloc_idmap (f, &t->map_vertex_g2l, num_vertices) );
-	TRY( h5priv_alloc_idlist_items (f, &t->sorted_lvertices, num_vertices) );
+	TRY( h5priv_alloc_idmap (f, &t->map_vertex_g2l, num) );
+	TRY( h5priv_alloc_idlist_items (f, &t->sorted_lvertices, num) );
 
 	return H5_SUCCESS;
 }
@@ -610,7 +609,6 @@ h5_err_t
 h5tpriv_close_file (
 	h5_file_t* const f		/*!< IN: file handle */
 	) {
-	TRY( release_memory (f) );
 	TRY( h5t_close_mesh (f) );
 
 	return H5_SUCCESS;
diff --git a/src/h5core/h5t_readwrite.c b/src/h5core/h5t_readwrite.c
index 14769d6..79fbee1 100644
--- a/src/h5core/h5t_readwrite.c
+++ b/src/h5core/h5t_readwrite.c
@@ -263,8 +263,13 @@ read_mtags (
 	h5_file_t* const f
 	) {
 	h5t_fdata_t* t = f->t;
-	TRY( t->mtags.group_id = h5priv_open_group (f, t->mesh_gid, "Tags") );
-	return h5tpriv_read_tag_container (f, &f->t->mtags);
+	h5_err_t exists;
+	TRY( exists = h5priv_hdf5_link_exists (f, t->mesh_gid, "Tags") );
+	if (exists) {
+		TRY( t->mtags.group_id = h5priv_open_group (f, t->mesh_gid, "Tags") );
+		TRY( h5tpriv_read_tag_container (f, &f->t->mtags) );
+	}
+	return H5_SUCCESS;
 }
 
 h5_err_t
diff --git a/src/h5core/h5t_ref_elements.c b/src/h5core/h5t_ref_elements.c
index 1e52897..016becd 100644
--- a/src/h5core/h5t_ref_elements.c
+++ b/src/h5core/h5t_ref_elements.c
@@ -1,37 +1,126 @@
 #include "h5core/h5_core.h"
 
+/*
+  
+  face: All kinds of sub-elements: vertices, edges, triangles ...
+  facet: co-dim 1 face
+  entities: all elements and faces of a grid
+ */
+
+/*
+ 2
+ **
+ *  *
+ *    *
+ *      *
+ *        *
+ *          *
+ *            *
+ 1              2
+ *                *
+ *                  *
+ *                    *
+ *                      *
+ *                        *
+ *                          *
+ *                            *
+ 0 * * * * * * * 0 * * * * * * *1
+
+*/
+
 const h5t_ref_elem_t h5t_tri_ref_elem = {
-	2,
-	{3, 3, 1}, // #vertices, #edges, #triangles
+	2,					// dimension
 	{
+		3,				// #vertices
+		3,				// #edges
+		1				// #triangles
+	},
+	{	// number of vertices per sub-element
 		[0] = {1, 1, 1},		// #vertices of vertices
 		[1] = {2, 2, 2},		// #vertices of edges
 		[2] = {3}			// #vertices of trinagles
 	},
-	{
+	{	// map sub-elements to vertices
 		[0] = {{0}, {1}, {2}},		// 3 vertices
 		[1] = {{0,1}, {0,2}, {1,2}},	// 3 edges
 		[2] = {{0,1,2}}			// 1 triangles
 	},
-	{{0.0, 0.0}, {1.0, 0.0}, {0.0, 1.0}},
+	{	// edges connected to vertex
+		[0] = {0,1},
+		[1] = {0,2},
+		[2] = {1,2}
+	},
+	{	// triangles connected to vertex
+		[0] = {0},
+		[1] = {0},
+		[2] = {0}
+	},
+	{	// coordinates
+		{0.0, 0.0},
+		{1.0, 0.0},
+		{0.0, 1.0}
+	}
 };
 
+
+/*
+ 3
+ **
+ ** *
+ * *  *
+ *  *   *
+ *   *    *
+ *    5     *
+ *     *      *
+ 3      *       4
+ *   2   *    3   *
+ *        2         *
+ *       *    *       *
+ *     *          *     *
+ *   1       0        2   *
+ * *                      * *
+ **                          **
+ 0 * * * * * * * 0 * * * * * * *1
+
+ Front face is {0,1,3} with id 1
+*/
+
 const h5t_ref_elem_t h5t_tet_ref_elem = {
-	3,
-	{4, 6, 4, 1}, // #vertices, #edges, #triangles, #tetrahedra
+	3,					// dimension
 	{
+		4,				// #vertices
+		6,				// #edges
+		4,				// #triangles
+		1				// #tetrahedra
+	},
+	{	// number of vertices per sub-element
 		[0] = {1,1,1,1},		// #vertices of vertices
 		[1] = {2,2,2,2,2,2},		// #vertices of edges
-		[2] = {3,3,3,3},			// #vertices of trinagles
+		[2] = {3,3,3,3},	       	// #vertices of trinagles
 		[3] = {4}			// #vertices of tets
 	},
-	{
+	{	// map sub-elements to vertices
 		[0] = {{0}, {1}, {2}, {3}},		 	  // 4 vertices
 		[1] = {{0,1}, {0,2}, {1,2}, {0,3}, {1,3}, {2,3}}, // 6 edges
 		[2] = {{0,1,2}, {0,1,3}, {0,2,3}, {1,2,3}},	  // 4 triangles
-		[3] = {{0,1,2,3}}					  // 1 tets
+		[3] = {{0,1,2,3}}      				  // 1 tets
 	},
-	{{0.0, 0.0, 0.0}, {1.0, 0.0, 0.0}, {0.0, 1.0, 0.0}, {0.0, 0.0, 1.0}},
+	{	// edges connected to vertex
+		[0] = {0,1,3},
+		[1] = {0,2,4},
+		[2] = {1,2,5},
+		[3] = {3,4,5}
+	},
+	{	// triangles connected to vertex
+		[0] = {0,1,2},
+		[1] = {0,1,3},
+		[2] = {0,2,3},
+		[3] = {1,2,3}
+	},
+	{	// coordinates
+		{0.0, 0.0, 0.0},
+		{1.0, 0.0, 0.0},
+		{0.0, 1.0, 0.0},
+		{0.0, 0.0, 1.0}
+	}
 };
-
-
diff --git a/src/h5core/h5t_ref_elements_private.h b/src/h5core/h5t_ref_elements_private.h
index bc1e191..2ed2a5d 100644
--- a/src/h5core/h5t_ref_elements_private.h
+++ b/src/h5core/h5t_ref_elements_private.h
@@ -8,4 +8,6 @@
 
 #define h5tpriv_ref_elem_get_dim(this) (this->ref_elem->dim)
 
+#define h5tpriv_get_edge_connected_to_vertex(this,face_idx, i) (this->edges_connected_to_vertex[face_idx][i])
+#define h5tpriv_get_facet_connected_to_vertex(this,face_idx, i) (this->edges_connected_to_vertex[face_idx][i])
 #endif
diff --git a/src/h5core/h5t_store.c b/src/h5core/h5t_store.c
index d8fe9ba..5f6f67c 100644
--- a/src/h5core/h5t_store.c
+++ b/src/h5core/h5t_store.c
@@ -93,6 +93,15 @@ assign_glb_elem_data (
 		h5_generic_elem_t *glb_elem = h5tpriv_get_glb_elem (f, loc_idx);
 
 		glb_elem->parent_idx = loc_elem->parent_idx;
+		if (loc_elem->parent_idx >= 0) {
+			h5_generic_elem_t *loc_parent = h5tpriv_get_loc_elem (
+				f, loc_elem->parent_idx);
+			h5_generic_elem_t *glb_parent = h5tpriv_get_glb_elem (
+				f, glb_elem->parent_idx);
+			
+			glb_parent->child_idx = loc_parent->child_idx;
+		}
+
 		glb_elem->child_idx = loc_elem->child_idx;
 
 		h5_id_t* glb_indices = h5tpriv_get_glb_elem_vertex_indices (f, loc_idx);
diff --git a/src/h5core/h5t_tags.c b/src/h5core/h5t_tags.c
index 0331d75..711e5ea 100644
--- a/src/h5core/h5t_tags.c
+++ b/src/h5core/h5t_tags.c
@@ -79,7 +79,7 @@ release_container (
 	if (ctn->num_sets == 0) return H5_SUCCESS;
 	TRY ( h5priv_hwalk ( f, &ctn->sets, release_tagset ) ); 
 	TRY ( h5priv_free ( f, ctn->names ) );
-
+	memset (ctn, 0, sizeof (*ctn));
 	return H5_SUCCESS;
 }
 
@@ -805,7 +805,7 @@ read_tagset (
 	hid_t dset_id;
 	ssize_t ssize;
 	TRY( (ssize = h5priv_get_hdf5_objname_by_idx (f, loc_id, idx, NULL, 0)) );
-	TRY( (name = h5priv_calloc (f, 1, ssize)) );
+	TRY( (name = h5priv_calloc (f, 1, ++ssize)) );
 	TRY( h5priv_get_hdf5_objname_by_idx (f, loc_id, idx, name, ssize) );
 	TRY( group_id = h5priv_open_hdf5_group (f, loc_id, name) );
 
diff --git a/src/h5core/h5t_types_private.h b/src/h5core/h5t_types_private.h
index a707e01..01e6922 100644
--- a/src/h5core/h5t_types_private.h
+++ b/src/h5core/h5t_types_private.h
@@ -6,10 +6,6 @@ typedef struct h5_vertex {
 	h5_coord3d_t	P;
 } h5_vertex_t;
 
-typedef struct h5_vertex_data {
-	h5_idlist_t	tv;
-} h5_vertex_data_t;
-
 typedef struct h5_triangle {
 	h5_id_t		idx;
 	h5_id_t		parent_idx;
@@ -56,6 +52,10 @@ typedef struct h5_dtypes {
 } h5_dtypes_t;
 
 typedef struct h5t_adjacencies {
+	struct {
+		h5_size_t size;
+		h5_idlist_t *v;
+	} tv;
 	h5_hashtable_t te_hash;
 	h5_hashtable_t td_hash;
 } h5t_adjacencies_t;
@@ -174,7 +174,6 @@ typedef struct h5t_fdata {
 
 	/*** vertices ***/
 	h5_vertex_t	*vertices;
-	h5_vertex_data_t *vertices_data;
 	h5_size_t	*num_vertices;
 	h5_idmap_t	map_vertex_g2l;	/* map global to local idx */
 	h5_idlist_t	sorted_lvertices;
diff --git a/src/include/h5core/h5t_ref_elements.h b/src/include/h5core/h5t_ref_elements.h
index f925ef5..bd7efcf 100644
--- a/src/include/h5core/h5t_ref_elements.h
+++ b/src/include/h5core/h5t_ref_elements.h
@@ -10,6 +10,8 @@ typedef struct {
 	int num_faces[H5T_MAX_DIM+1];
 	int num_vertices_of_face[H5T_MAX_DIM+1][H5T_MAX_FACES];
 	int map[H5T_MAX_DIM+1][H5T_MAX_FACES][H5T_MAX_VERTICES];
+	int edges_connected_to_vertex[H5T_MAX_VERTICES][H5T_MAX_FACES];
+	int triangles_connected_to_vertex[H5T_MAX_VERTICES][H5T_MAX_FACES];
 	h5_float64_t coords[H5T_MAX_VERTICES][H5T_MAX_DIM];
 } h5t_ref_elem_t;