This document provides human machine interface (HMI) design specifications for keyless ignition systems that use key code carrying device for passenger cars (including sport utility vehicles and light trucks) and commercial vehicles (including heavy trucks and buses), independent of vehicle propulsion system. HMI specifications for the electrical key functions include actuation in normal conditions, emergencies, low battery, and avoidance of inadvertent actuations, alerts and specific non-standard situations.st edition 2019-11 Road vehicles — Ergonomics aspects of transport information and control systems — Human machine interface specifications for keyless ignition systems Véhicules routiers — Aspects ergonomiques des systèmes de commande et d'information du transport — Spécifications d'interface homme-machine pour des systèmes de démarrage sans clé Reference number ISO 21956:2019(E) ？ ISO 2019 ISO 21956: 標準截圖