How to handle the use of P81a and P81b in the Target Model?

[stephenhart8]

It has been decided early on in the elaboration of the Target Model that dates should only be documented through the most encompassing bounds, in other words the earliest and latest moments an event could have happened, which are modelled with the properties P82a_begin_of_the_begin and P82b_end_of_the_end.

However, in some circumstances, the sole use of those external limits can be problematic. This could be the case for a painting occupation that would be known from some painting production. The begin date of the occupation would necessarily be BEFORE the date of the earliest painting production. In terms of CIDOC CRM entities, that would mean that the beginning of the E52_Time-Span of the F52_Pursuit event ended when this first known artwork was produced, which requires the use of the property P81a_end_of_the_begin.

How could such cases be handled in the TM? Should we:

• add more flexibility in the date pattern, and allow the use of any of the 4 properties P81a, P81b, P82a and P82b? This would create much more complications for the inexperienced user;
• not allow the use of the properties P81a and P81b, thus losing some expressiveness in the model in favour of simplifying the understanding of dates? With this approach, the painting occupation example would have no date begin;
• have a case by case study of such cases, which would create a heavier burden on the shoulders of both CHIN and the institution modelling its data? This is the solution that is temporary in use, as it is recommended to contact CHIN if the provider wants to use P81a and P81b.

Are there other solutions for this issue?