BS EN ISO 6149-1:2019 Connections for hydraulic fluid power and general use. Ports and stud ends with ISO 261 metric threads and O-ring sealing Ports with truncated housing for O-ring seal

Stud couplings
Screwed fittings
Dimensions
Pneumatic transmission systems
Threads
Orifices
Toroidal sealing rings
Identification methods
Hydraulic transmission systems
Holes
Service pressure
Marking
Pipe fittings
Pipe couplings

Link: BS EN ISO 6149-1:2019 Connections for hydraulic fluid power and general use. Ports and stud ends with ISO 261 metric threads and O-ring sealing Ports with truncated housing for O-ring seal
Source: BSI Standards