Premise: Buddha's Dispensation (Buddha-sasana) is the time period which Dharma (Pali Canon) exist and follow. It is totally 5000 years after the Buddha's Parinirvana (pass away or "Skandha Parinirvana"). There are three types of Parinirvana those are "Klesha Parinirwana", "Skandha Parinirvana" and "Dhatu Parinirvana".
Hypothesis: Parinirvana is something everyone understands right away.