GENERAL This standard for Metric Oval 90º Countersunk Head Type IA Cross Recess Tapping Screws of thread cutting Types D, F and T conforms in all essentials with the American National Standard covering metric tapping screws. It should be noted that, for most screw sizes, the head diameters specified herein differ from those documented on previously issued detail drawings. Therefore, it is recommended that any countersink provisions in existing designs, based on earlier metric oval head screw dimensions, be reviewed and adjusted accordingly. Also, for the most part, the Type 1A cross recess configuration will serve to identify these screws as being metric.