ISO 20383:2017 specifies the dimensions, characteristics, and positioning of Speed Identification Signs (SIS). These signs indicate the maximum equipment ground speed, based on the ground speed design capability, for an agricultural vehicle.
A rear-facing SIS is visible to other operators on public roads approaching the equipment from behind. A forward-facing SIS, mounted on the front of towed equipment, alerts operators of the towing vehicle of the maximum specified ground speed capabilities at which the equipment combination can be operated.
ISO 20383:2017 is applicable to self-propelled, semi-integral and towed equipment moving on public roads.