Ascertainable

For example, when regulation prevents a developer from building rental property, the value of existing or reasonably ascertainable leases represents an opportunity cost of the prohibition to the developer.

The easily ascertainable fact, they point out, is that what they feel is not anger toward parents speaking Lennon's name, but only contempt for the few so ignorant of cultural history that they think it was John Lennon, instead of Paul McCartney, who sang "Why Don't We Do It in the Road?"

The real responsibility, the reasons behind the assassination, were still in dispute half a century later. But even events that are less crucial are still often incompletely ascertainable.