DTV12 — No indefinite time point sequences

In clause 8.7, the definition of time point sequence corresponds to time interval assumes that each time point sequence has a first time point and a last time point. Further, v1.1 introduced the “time points” primordial and perpetuity to provide the means for specifying indefinite time periods. That creates time points to be the first and last time points of the time point sequences that correspond to indefinite time periods.

We must either redefine the correspondence concept or remove the possibility that there is no first/last time point. The latter simplifies the model. (Note also that most indefinite time periods DO have a last time point, we just don’t know what it is.)

The RTF agrees that indefinite time point sequences are problematic. The text should recommend the use of ‘primordial’ and ‘perpetuity’ when those are explicitly intended. But when the first or last time point of a time point sequence is simply “unknown”, that is not clearly appropriate. In any case, however, every time point sequence has a first time point and a last time point, and the text is revised to eliminate features and wording that suggest otherwise.