Information about Gain of Role and Loss of Role

BFO roles are realizable entities external to (i.e., not intrinsic to) the bearer. Roles are assigned to a bearer in a physical, social, or institutional set of circumstances and the bearer does not cease to exist when it stops bearing a role. Due to these reasons, a single bearer may bear multiple roles throughout its lifetime, e.g., the same person can bear a buyer role (iof:BuyerRole), a customer role (iof:CustomerRole), and a supplier role (iof:SupplierRole) at different time periods. But multiple roles can also be held concurrently by a single bearer. However, BFO does not provide a way to express the time when the bearer has started or stopped bearing a role and for how long the role was held. 

To fill in these shortcomings, two new subclasses of bfo:process were introduced to IOF Core. Users can use the two processes to express exact or relative time points (relative to the time region the processes occupy) when a role started or stopped existing. However, flexibility is provided where the exact starting and stopping time points during the process are not required. This allows the user to choose a suitable scheme for representing the time of gaining and losing the role in a variety of ways per their data requirements. The classes are also axiomatized such that the bearer of the role is clear (as a participant in the process).