DTV — Annex D should be Normative

The Date/Time Annex D "Fundamental Concepts" says that it is 'informative'. But the declarations and definitions in Annex D are formally specified in SBVR and UML. Moreover, the UML classes and associations defined in Annex D are used directly in the formal normative specifications in the body of Date/Time. The 'quantities' model (D.3) is used in peripheral way in defining 'duration' and 'time unit', and might be considered informative only, since only some 'time units' are 'measurement units' (as defined in D.3). But the part/whole relationship (D.4) is used normatively in clause 8, and the sequences (D.1) and scales (D.3) concepts are critical to the formulation of definitions and necessities in clause 8 and in clause 12. So, it appears that Annex D.1, D.2 and D.4 are critical to the normative specification.

It is the stated intent of the Date/Time specification that the Annex D models are outside the scope of the Date/time specification, and are used only because no appropriate formal specification of these concepts has been found. Thus a later specification with focused expertise in these areas can be expected to supplant these elements of the Date/Time specification at some future time. Nonetheless, the text of the Date/Time specification, and its formal models, depend on Annex D being interpreted normatively until some future time when it is formally replaced by a specification with wider support.
Recommendation: Make Annex D 'normative', and retain the caveat that it is an interim specification.

The FTF proposes to make Annex D.2 “Sequences” and Annex D.4 “Mereology” normative, and leave Annex D.3 “Quantities Vocabulary” informative. The “Sequences” and “Mereology” vocabularies are complete and self-consistent, and do not overlap with any other known standards effort. The “Quantities Vocabulary” annex deliberately addresses only the subset of the Quantities topic that is needed by the Date-Time Vocabulary. Other efforts – the QUDV activity of SysML and the QUOMOS standards work at OASIS – are working in this area. Consequently, the FTF prefers to keep the “Quantities Vocabulary” informative.