DTV12 — Necessities should be independent of placement

Specification: DTV

Version: 1.1

Source: Ed Barkmeyer, NIST, edbark(at)nist.gov

Summary:

In the Date Time Vocabulary v1.0 specification, clause 16.5 contains the following terminological entry:

individual situation kind has occurrence interval

Definition: the occurrence interval is the time span of the individual situation kind

Necessity: The individual situation kind has exactly one occurrence

...

In the Necessity, "the individual situation kind" is intended to refer to whatever plays the 'individual situation kind' role in an instance of the verb concept (wording). But that interpretation can only be made when the Necessity appears in the verb concept entry. SBVR practice is to make the meaning of the Necessity independent of where it is stated. To be consistent with SBVR practice, the above Necessity should read:

Each individual situation kind that has an occurrence interval has exactly one occurrence.

There are several Necessities in DTV that use this dubious form of reference. Each of them should be reformulated in the SBVR location-independent style.

After consultation with SBVR experts (see SBVR Issue 19361), the RTF agrees.
There is a standard pattern to the revised Necessity statements. The pattern is:
Each <subject> that <rest of verb concept wording> <rest of Necessity>.
For the example given, the result is:
Each individual situation kind that has an occurrence interval has exactly one occurrence.
This pattern is applied to binary verbs, but it does not work well for ternary verbs, and other approaches were used to phrase those Necessities correctly.
Some of the Necessities about occurrence intervals were redundant, because they were implied by the corresponding Necessities for time intervals.
Several occurrences of the problem were omitted from this resolution because another issue corrects the same text.