diff --git a/.gitattributes b/.gitattributes
index e544826..1973d25 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -392,6 +392,8 @@ src/h5_core/h5_qsort_r.c -text
 src/h5_core/h5_readwrite.c -text
 src/h5_core/h5_readwrite.h -text
 src/h5_core/h5_readwrite_private.h -text
+src/h5_core/h5_syscall.c -text
+src/h5_core/h5_syscall_private.h -text
 src/h5_core/h5_types.h -text
 src/h5_core/h5b_errorhandling_private.h -text
 src/h5_core/h5t_boundaries.c -text
@@ -410,6 +412,7 @@ src/h5_core/h5t_readwrite_private.h -text
 src/h5_core/h5t_storemesh.c -text
 src/h5_core/h5t_storemesh.h -text
 src/h5_core/h5t_storemesh_private.h -text
+src/h5_core/h5t_types_private.h -text
 src/h5_core/h5u_errorhandling_private.h -text
 src/h5_core/h5u_readwrite.c -text
 src/h5_core/h5u_readwrite.h -text
diff --git a/src/h5_core/h5_syscall.c b/src/h5_core/h5_syscall.c
new file mode 100644
index 0000000..0ba7864
--- /dev/null
+++ b/src/h5_core/h5_syscall.c
@@ -0,0 +1,15 @@
+#include <stdlib.h>
+#include <hdf5.h>
+#include "h5_core.h"
+#include "h5_core_private.h"
+
+void *
+_h5_alloc (
+	void *ptr,
+	const size_t size ) {
+	ptr = realloc ( ptr, size );
+	if ( ptr == NULL ) {
+		return (void*)HANDLE_H5_NOMEM_ERR;
+	}
+	return ptr;
+}
diff --git a/src/h5_core/h5_syscall_private.h b/src/h5_core/h5_syscall_private.h
new file mode 100644
index 0000000..a97f28a
--- /dev/null
+++ b/src/h5_core/h5_syscall_private.h
@@ -0,0 +1,9 @@
+#ifndef __H5_SYSCALL_H
+#define __H5_SYSCALL_H
+
+void *
+_h5_alloc (
+	void *ptr,
+	const size_t size );
+
+#endif
diff --git a/src/h5_core/h5t_types_private.h b/src/h5_core/h5t_types_private.h
new file mode 100644
index 0000000..6c8c8ff
--- /dev/null
+++ b/src/h5_core/h5t_types_private.h
@@ -0,0 +1,139 @@
+#ifndef __H5T_TYPES_PRIVATE_H
+#define __H5T_TYPES_PRIVATE_H
+
+
+struct h5_vertex {  /* 32Byte */
+	h5_id_t		id;
+	h5_id_t		unused;	/* for right alignment */
+	h5_float64_t	P[3];
+};
+typedef struct h5_vertex	h5_vertex_t;
+
+struct h5_edge { /* 16Bytes */
+	h5_id_t		id;
+	h5_id_t		parent_id;
+	h5_id_t		refined_on_evel; /* = 0 if not refined*/
+	h5_id_t		unused;	/* for right alignment */
+	h5_id_t		vertex_ids[2];
+};
+typedef struct h5_edge		h5_edge_t;
+
+struct h5_triangle { /*24Bytes*/
+	h5_id_t		id;
+	h5_id_t		parent_id;
+	h5_id_t		vertex_ids[3];
+	h5_id_t		refined_on_level;
+};
+typedef struct h5_triangle	h5_triangle_t;
+
+struct h5_tetrahedron { /* 24Bytes */
+	h5_id_t		id;
+	h5_id_t		parent_id;
+	h5_id_t		refined_on_level;
+	h5_id_t		unused;	/* for right alignment */
+	h5_id_t		vertex_ids[4];
+};
+typedef struct h5_tetrahedron	h5_tetrahedron_t;
+
+struct h5_ltriangle {
+	h5_id_t		vertex_ids[3];	/* local(!) vertex ids */
+};
+
+struct h5_ltetrahedron {
+	h5_id_t		vertex_ids[4];	/* local(!) vertex ids */
+};
+
+union entities {
+	struct h5_tetrahedron	*tets;
+	struct h5_triangle	*tris;
+	void			*data;
+};
+
+union lentities {
+	struct h5_ltetrahedron	*tets;
+	struct h5_ltriangle	*tris;
+	void			*data;
+};
+
+
+struct boundary {
+	char		name[16];
+	char		label[256];
+	h5_id_t		id;			/* name of boundary as integer */
+	h5_id_t		changed;		/* true if boundary is new or
+						   has been changed */
+	h5_id_t		gid;			/* hdf5 grp id boundary */
+	h5_id_t		*faces;
+	h5_id_t		*lfaces;
+	h5_size_t	*num_faces;		/* addit. num of faces per level */
+	h5_size_t	*num_faces_on_level;	/* real num of faces per level */
+	
+	h5_id_t		last_accessed_face;
+};
+typedef struct boundary boundary_t;
+
+struct h5t_fdata {
+	/*** book-keeping ***/
+	char		mesh_name[16];
+	char		mesh_label[256];
+	enum h5_oid	mesh_type;
+	h5_id_t		cur_mesh;
+	h5_id_t		mesh_changed;		/* true if mesh is new or has
+						   been changed		*/
+	h5_id_t		num_meshes;
+	hid_t		entity_tid;		/* HDF5 type id: tet, triangle
+						   etc			*/
+
+	h5_id_t		cur_level;
+	h5_id_t		new_level;		/* idx of the first new level
+						   or -1		*/
+	h5_size_t	num_levels;
+
+	/*** vertices ***/
+	h5_vertex_t	*vertices;
+	h5_size_t	*num_vertices;
+	struct idmap	map_vertex_g2l;		/* map global id to local id */
+	struct smap	sorted_lvertices;
+	h5_id_t		last_retrieved_vertex_id; 
+	h5_id_t		last_stored_vertex_id; 
+
+
+	/*** Entities ***/
+	union entities	entities;
+	union lentities lentities;		/* local vertex id's of
+						   entities		*/
+	h5_size_t	*num_entities;
+	h5_size_t	*num_entities_on_level;
+	struct idmap	map_entity_g2l;		/* map global id to local id */
+
+	struct smap				/* array with geometrically */
+	sorted_lentities[H5_MAX_VERTICES_PER_ENTITY];/*  sorted local entitiy ids
+							 [0]: 0,1,2,3 sorted 
+							 [1]: 1,0,2,3 sorted */
+
+	h5_id_t		last_retrieved_entity_id; 
+	h5_id_t		last_stored_entity_id;
+
+	/*** Boundary Meshes ***/
+	h5_id_t		num_boundaries;		/* number of boundaries */
+	h5_id_t		boundaries_gid;		/* hdf5 grp id container group */
+
+	boundary_t	boundary;
+
+	/*** HDF5 objects ***/
+	hid_t		topo_gid;		/* grp id of mesh in current
+						   level		*/
+	hid_t		meshes_gid;
+	hid_t		mesh_gid;
+
+	/*** type ids' for compound types ***/
+	hid_t		float64_3tuple_tid;	/* 3-tuple of 64-bit float */
+	hid_t		int32_2tuple_tid;	/* 2-tuple of 32-bit int */
+	hid_t		int32_3tuple_tid;	/* 3-tuple of 32-bit int */
+	hid_t		int32_4tuple_tid;	/* 4-tuple of 32-bit int */
+	hid_t		vertex_tid;		/* vertex structure */
+	hid_t		triangle_tid;		/* triangle structure */
+	hid_t		tet_tid;		/* tetrahedron structure */
+};
+
+#endif