IEC 61837-2:2011 deals with standard outlines and terminal lead connections as they apply to surface-mounted devices (SMD) for frequency control and selection in ceramic enclosures, and is based on IEC 61240. In this edition, types of enclosures are renamed to express their features in their names for better understanding. The relative comparison of new types with old ones is listed in Table 1. New names of enclosures express configuration type, terminal lead numbers, sizes and arrangement of terminal pads. The details of definition are shown in Clause 3: Configuration of enclosures, and Clause 4: Designation of types. Enclosures in this new edition are based on IEC 61240. In this standard, 27 enclosures are added to the first edition of IEC 61837-2.