To Be Determined
I think the best practice has been clear for 4-5 years now
_:birth_timespan a E52_Time-Span; crm:P3_has_note "[DISPLAY DATE]"; crm:P82a_begin_of_the_begin "[EARLIEST_DATE]"^^xsd:date; # or "[EARLIEST_YEAR]"^^xsd:gYear crm:P82b_end_of_the_end "[LATEST_DATE]"^^xsd:date. # or "[LATEST_YEAR]"^^xsd:gYear
_:birth_timespan a E52_Time-Span; P3_has_note [DISPLAY DATE]; P79_beginning_is_qualified_by [QUALIFIER]; P80_end_is_qualified_by [QUALIFIER]; P82_at_some_time_within [DATE].
Where did you get this from? Can you give examples of these qualifiers?
(Vladimir 12/14/2016) To make it clear: P79 "qualifies the beginning of an E52 Time-Span in some way. The nature of the qualification may be certainty, precision, source etc": this is not at all the date itself. In my practice I've never seen separate qualifiers for beginning/end, so never used P79/80.
When the date is uncertain (a range), use
crm:P82b_end_of_the_end (actually P82a&b are defined as sub-props of P82, so you may get two P82 depending on reasoning). When the date/year is certain, use
If the data describes a period (frbroo:F51_Pursuit aka "active" or "floruit") rather than a "point" event, definitely use P82a/b.