IEC 61837-4:2015 specifies the outline drawings and terminal lead connections for surface piezoelectric devices with hybrid enclosure outlines and is based on IEC 61240:2012 which standardized layout rules of outline drawings of surface-mounted device. This edition includes the following significant technical changes with respect to the previous edition:- Outline drawing is defined as one set of drawings consisting of four views, which are the view from above, the front view, the view from the right, and the view from below, instead of one set consisting of three views as provided in the previous edition.- The configurations of the enclosures were revised as shown in Table 1.