This document specifies dimensional and functional requirements for the compatible mounting of switchgear, controlgear and accessories on some types of rails. The object of this document is to specify those dimensions that are critical for the correct design of mounting rails and equipment. The following sections are covered by this document: \'top hat\' section; \'C\' section; \'G\' section. NOTE1 Mounting compatibility does not imply functional interchangeability. Annexes deal with specific steel mounting rails satisfying the requirements of this document, and give additional dimensional data and loading requirements applicable to such rails. NOTE2 The detailed design and material of specific steel rails is given in the annexes. NOTE3 Other shapes of rails complying with this document not listed in AnnexA can be used. Mounting rails used as a protective conductor using a conducting connection to a protective conductor terminal block are specified in IEC60947‑7‑2 . In other applications where the mounting rail is used as earthing conductor, the relevant product standard applies. This document has the status of a horizontal standard in accordance with IECGuide108:2006 . This horizontal standard is primarily intended for use by technical committees in the preparation of standards in accordance with the principles laid down in IECGuide108 . One of the responsibilities of a technical committee is, wherever applicable, to make use of horizontal standards in the preparation of its publications. The contents of this horizontal standard will not apply unless specifically referred to or included in the relevant publications.