DTV — no syntax for indefinite time periods

A time interval that starts at a definite time (be it "now", or "starting when 13 states have signed the declaration", or "starting when the exchange offers our stock on the floor", and continues without end is a different kind of "forever" than the time period specified in 9.4.

Similarly, there are intervals that start at indefinite time in the past and end at a stated time ("now" or whatever). Such intervals are referred to in phrases such as "Until the Wildlife Protection Act goes into effect in 2016", where no event marks the start of the interval in question - only its end.
These are cases in which
a) a time period has a first time point but no last time point, or
b) a time period has a last time point but no first time point.

Unlike 'forever', which is unique, those categories of time period have infinitely many instances. And unlike time periods that have a start time and an end time, or a start time and a duration, the DTV does not provide a simple fact type for specifying them: the time interval 'after (time point)' or 'from (time point) on', and the time interval 'until (time point)'.

Some such fact types would clearly be useful in a business vocabulary.

The resolution of issue 17540 adds the concepts ‘primordiality’ and ‘perpetuity’ as individual time interval concepts. This resolution adds verb concepts such as ‘time interval1 to situation model specifies time interval2’ that can be used with any time interval, including ‘primordiality’ and ‘perpetuity’, to mean a time interval that extends until an occurrence of the situation model.