Gas cylinders -- Compilation of national and international valve stem/gas cylinder neck threads and their identification and marking system
ISO/TR 11364:2012 lists the different valve stem to gas cylinder connection threads currently and historically existing worldwide and provides official coded designations for them. These coded designations will then be available for identification and marking purposes.
It also gives guidance concerning which threads are dimensionally identical and which are interchangeable.
Furthermore, it provides guidance for valving procedures when fitting valves to gas cylinders.