ISO 21007-2:2015 establishes a common flexible framework for data structure to enable the unambiguous identification in gas cylinder (GC) applications and for other common data elements in this sector. ISO 21007-2:2015 enables a structure to allow some harmonization between different systems. However, it does not prescribe any one system and has been written in a non-mandatory style so as not to make it obsolete as technology changes. The main body of this part of ISO 21007 excludes any data elements that form any part of transmission or storage protocols such as headers and checksums. For details on cylinder/tag operations, see Annex A.