“Dynamic Driving Task (DDT)” means the real-time operational and tactical functions required to operate the vehicle.
GR
from the French “Groupe de Rapporteurs”; signifies any of the permanent working parties subsidiary to WP.29 (e.g. on noise, lighting, pollution and energy, passive safety, etc.)
GRPE
Working Party on Pollution and Energy (cf French: Groupe de Rapporteurs sur la Pollution et l’Energie)