2015NF E48-050-4:2015 Connections for fluid power and general use - Ports and stud ends with ISO 261 metric threads and O-ring sealing - Part 4 : dimensions, design, test methods and requirements for external hex and internal hex port plugs
0000 NF E48-050-4:2006
1979NF E27-431:1979 Threaded core plugs and threaded slotted pipe plugs.