The IEC 62873 series covers available common standards intended to be used in conjunction with or for the preparation of RCD (residual current device) standards. This part of IEC 62873 defines the methodology and processes used when producing standards based on a new approach (hereafter referred to as blocks and modules) aiming at harmonizing a family of standards, thus avoiding mistakes, inconsistencies or discrepancies within this family of standards. The family of standards considered in this document consists of standards for RCCBs (Residual Current Circuit-Breakers without overcurrent protection), RCBOs (Residual Current Circuit-Breakers with overcurrent Protection), and general safety requirements for residual current operated protective devices (namely IEC 61008-1, IEC 61009-1 and IEC TR 60755). This approach defines a way to optimize drafting of standards, aiming to keep a common or similar structure, to have common clauses (as far as possible), to avoid inconsistencies, to do editorial work only once, to speed up production of standards, to ensure that a comment on one clause in one standard is also taken into account in other standards, if needed. The principles of the blocks and modules approach are: to identify those parts of the standards which need to be identical (or with limited differences), and those parts of the standards which should remain different; to set a library of those common parts; to identify the parts which should be published as stand-alone standards; to draft product standards, using the library; to keep track of the common parts used in a product standard when revision will be needed in the future. This document also lists the available blocks and modules which were prepared for RCD product standards.