 Grammatical tense

Grammatical tense locates an event or state relative to a temporal reference point, commonly the time of speaking. A language may mark it through verb forms or grammatical constructions. Temporal reference itself is broader: a time expression can convey when something happens without being a tense marker.^[ref]

In the simple past statement “The train arrived”, the arrival precedes the speech time. Writing event time $E$ and speech time $S$, this simple relation is $E<S$. “The train was arriving” also has past tense, but changes grammatical aspect by presenting the arrival as unfolding. Thus the two categories answer different questions. A precise model states its reference point and interpretation; identifying a past-looking ending alone does not settle every temporal relation in a complex utterance.