As of the last revision (2023), J1939-73 has expanded significantly to cover cybersecurity (J1939-91) and high-voltage safety for electric commercial vehicles. The "exclusive" PDFs of the future will include diagnostic definitions for battery management systems (BMS) and electric axle drives.
SAE meets ISO: Description of SAE J1939-73 ... - ResearchGate
Provides protocols for reading and writing to the ECU (Electronic Control Unit).