DTV 1.0b2 FTF Avatar
  1. OMG Issue

DTV — Time point subdivision is out of place twice

  • Key: DTV-27
  • Legacy Issue Number: 16951
  • Status: closed  
  • Source: Thematix Partners LLC ( Edward Barkmeyer)
  • Summary:

    At the end of section 9.3 the fact type 'finite time scale subdivides time point' is defined and depicted in Figure 9-6. This fact type is a commonly used property of finite time scales, and is not specific to individual time points. That is, the finite time scale day-of-hours subdivides every day-of-month, for example. So the text and diagram should be at the end of 9.2, where finite time scale is defined.

    Also, diagram 9-6 does not show the operations on time point and finite time scale that are associated with this fact type and shown in diagram 12-12.

    Finally, diagram 12-12 (section 12.4) shows this fact type as well, but section 12.4 never uses it, and diagram 12-12 shows a <<specialization>> relationship that is never discussed anywhere in the text. If the relationship is important, it should be discussed. Otherwise, the subdivision association is out of place in diagram 12-12 and the "specialization" dependency should be deleted from the UML model.


    Move the diagram and text for 'finite time scale subdivides time point' to the end of 9.2, include the operations on the diagram. Delete the fact type from diagram 12-12, and delete the "specialization" dependency altogether.

  • Reported: DTV 1.0b1 — Tue, 10 Jan 2012 05:00 GMT
  • Disposition: Resolved — DTV 1.0b2
  • Disposition Summary:

    The FTF agrees that the fact-type 'finite time scale subdivides time point' should be moved, along with Figure 9-6, but it depends on concepts defined in 9.3 and 9.4. It is an important concept that should have its own subsection. This concept is used only in defining finite time scales within Calendars. So the new section goes in clause 10 (formerly 9.5) Calendars.
    The verb concept 'finite time scale subdivides time point' is not quite the way it is used. All of the existing usages have the form: 'finite time scale subdivides time point into number of time point kind.' But the finite time scale determines the time point kind, so that is redundant. Also, it is not clear whether the intent is to specify the cardinality of the finite time scale or the cardinality of the time point sequence that is the subdivision of individual time points, such as months of the year. The text is revised to distinguish subdivides as a characteristic of finite time scales from the specification of the actual time point sequences used to subdivide individual time points. The term exactly subdivides is used when all the time points have the same subdivision; and the special cases use the (now defined) verb 'time point has number of time point kind' that was already present in the entries for the special cases.
    Note: This clarification was not applied to the 'year of weeks' and 'year of weekdays' time scales, whose nature is addressed by a different issue. Simply stated, the year of weeks does not subdivide a calendar year.
    The concept in diagram 10.14 (formerly 12.12) – time point converts to time point sequence on time scale – is only distantly related. The nature of the time point sequences involved is different, and the purposes are different. The purpose of time point subdivision is to be part of the definition of finite time scales. Diagram 10.14 (formerly 12.12) no longer shows the "specialization"; it was removed by resolution of another issue.

  • Updated: Fri, 6 Mar 2015 20:58 GMT