IEC 60601-2-25:2011 applies to the basic safety and essential performance of electrocardiographs intended by themselves or as a part of a medical electrical system, for the production of electrocardiogram reports for diagnostic purposes. The equipment intended for use under extreme or uncontrolled environmental conditions outside the hospital environment or physician's office, such as in ambulances and air transport, shall comply with this particular standard. Additional standards may apply to Medical electrical equipment for those environments of use. Not included within the scope of this particular standard are: a) the part of Medical electrical equipment that provides vectorcardiographic loops; b) ambulatory electrocardiographic medical electrical equipment covered by IEC 60601-2-47 where not intended for obtaining electrocardiogram reports for diagnostic purposes; c) cardiac monitors covered by IEC 60601-2-27 where not intended for obtaining electrocardiographic reports for diagnostic purposes. This second edition cancels and replaces the first edition of IEC 60601-2-25, published in 1993 and the first edition of IEC 60601-2-51, published in 2003. Updating the particular standards to refer to the third edition of the general standard provided the opportunity to merge the first editions of IEC 60601-2-25 and IEC 60601-2-51 into one standard. Reformatting and technical changes were both made. This second edition of IEC 60601-2-25 constitutes a technical revision of both those standards.