DTV11 — Time intervals defined by duration

In DTV Beta-2,Clause 8.2.3, there are two verb concepts:
time interval1 is duration before time interval2
time interval1 is duration after time interval2

From the alternative form: "duration before/after time interval2", it seems clear that the intent of these verb concepts is to allow a time interval to be defined by a reference time interval and a duration, e.g., the two weeks before the jump-off date, the day after the meeting (day). Each of these denotes exactly one time interval.

But the Definitions mean that the verb concepts simply state the duration between two time intervals. This may be useful when the intent is to state the duration between two events, but it is not the meaning of 'duration before time interval', and it cannot be used to define a time interval. Either these verb concepts should be defined to be the ones intended by the alternative forms, or the alternative forms should be separate verb concepts.

The intent of these two verb concepts is to define time intervals, but there are two ways to define time intervals in terms of durations. ‘the two weeks before the meeting’ refers to a time period of two weeks, ending with the meeting, as the issue describes. ‘two weeks before the meeting’ refers to a time interval (a day) that is separated from the meeting by two weeks, which is the intent of the existing text. The concepts in the issue statement are additional concepts, not replacement concepts. They are added.
The RTF also notes that the most common bases for duration before and after are used with events rather than time intervals. This simplifies the business usage by avoiding the circumlocution ‘the time interval when ...’. The corresponding verbs are added to clause 16. These are simplifications of concepts that use the verb concepts at issue.
Clause 16.7 was already very large. The edit also formally creates two subsections at the obvious boundary.