Please refer to IATA Dangerous Goods Regulations, Appendix A – Glossary, and look up the definition for NET QUANTITY. It says, the NET QUANTITY means the weight or volume of the dangerous goods contained in a package excluding the weight or volume of any packaging material. For the purpose of this definition, ‘dangerous goods’ means the substance or article as described by the proper shipping name shown in Table 4.2, e.g., for “Fire Extinguishers” the net quantity is the weight of the fire estinguisher.
In the case of UN 1072 Oxygen, compressed, the NET QUANTITY is the net weight of the oxygen. If the PSN was shown as Oxygen bottle, thence the NET QUANTITY would include the weight of the bottle.
The definition of NET QUANTITY has been redefined effective with the 54th Edition DGR.