ddt = gras_datadesc_struct("ex_t");
gras_datadesc_struct_append(ddt,"msg",gras_datadesc_by_name("string"));
gras_datadesc_struct_append(ddt,"category",gras_datadesc_by_name("int"));
ddt = gras_datadesc_struct("ex_t");
gras_datadesc_struct_append(ddt,"msg",gras_datadesc_by_name("string"));
gras_datadesc_struct_append(ddt,"category",gras_datadesc_by_name("int"));