-int n_dim; /* Number of dimensions. */
-size_t *nv_dim; /* Number of variables in each dimension. */
-struct variable ***v_dim; /* Variables in each dimension. */
+static int n_dim; /* Number of dimensions. */
+static size_t *nv_dim; /* Number of variables in each dimension. */
+static struct variable ***v_dim; /* Variables in each dimension. */