SUBSET-026-4 v300,This document defines the modes of the ERTMS/ETCS on-board equipment (see chapter 4.4 “Definition of the modes” and chapter 4.5 “Modes and Class 1 functions”.
SUBSET-026-3 v300,The chapter 3, Principles, specifies the system principles of ETCS/ERTMS. These principles apply to on-board and trackside subsystems and are mainly derived from FRS.