BS EN IEC 61158-4-4:2019 Industrial communication networks. Fieldbus specifications Data-link layer protocol specification. Type 4 elements

Data transmission
Fieldbus
Communication procedures
Interfaces (data processing)
Automatic control systems
Communication networks
Process control
Industrial
Bus networks
Computer networks
Data link layer (OSI)
Open systems interconnection

Link: BS EN IEC 61158-4-4:2019 Industrial communication networks. Fieldbus specifications Data-link layer protocol specification. Type 4 elements
Source: BSI Standards