This document defines a physical layer having a robust immunity to EMI and physical properties suitable for harsh environments. CAN controllers are available which support the CAN Flexible Data Rate Frame Format. These controllers, when used on SAE J1939-11 networks, must be restricted to use only the Classical Frame Format compliant to ISO 11898-1:2015. These SAE Recommended Practices are intended for light- and heavy-duty vehicles on- or off-road as well as appropriate stationary applications which use vehicle derived components (e.g., generator sets). Vehicles of interest include but are not limited to: on- and off-highway trucks and their trailers; construction equipment; and agricultural equipment and implements.