(*) n u d : new / updated / deleted since previous version.

(**) Usage: The indications Mandatory / Conditional / Optional are to be understood in respect of the actual level of the Data element:
  example given; some party data-set as a whole can be optional, while, if present, the party's name within that party data-set can be mandatory.

Remark: in UN/Edifact, "Mandatory / Conditional" are notions used within the standard. And within edi-guides (a refinement of a standard) the "Conditional" can become "Required / Optional / Dependent / Advised / Not used". Ideally we should implement the same ideas.