Orientation Times: the universal role vocabulary for tense #

@cite{klein-1994} @cite{kiparsky-2002} @cite{reichenbach-1947} @cite{declerck-2006}

The contemporary linguistic literature on tense has largely converged on a four-element role vocabulary for the times that tense and aspect manipulate:

Utterance time (utterance): when the utterance is made. Klein's TU, Reichenbach's S, Declerck's t₀.
Topic time (topic): the time about which a claim is made. Klein's TT, Reichenbach's R. Sometimes called "reference time" in older Reichenbachian usage; "topic time" is now standard.
Situation time (situation): when the described situation actually obtains. Klein's TSit, Reichenbach's E, Declerck's TS, Kratzer's "running time of the event" τ(e).
Perspective time (perspective): the time tense locates the topic against. Kiparsky's P (= utterance in root clauses, but shifts under free indirect discourse, attitude embedding, narrative mode). Declerck's TO₁ (the binding TO of the domain) plays the same architectural role, even though Declerck does not use the "perspective" label.

The fifth case sub (n : Nat) covers framework-specific intermediate TOs: Declerck's TO₂, TO₃, etc. in chained tenses (past perfect, conditional perfect). The natural-number index counts outward from the perspective TO: Declerck's TO₂ is sub 0, TO₃ is sub 1. This keeps the universal vocabulary closed while admitting arbitrarily-long chains.

Orientation is the canonical Role type used by Domain, TenseSystem, and AspectSystem in the rest of the temporal substrate. Framework-specific role mappings (Reichenbach → {utterance, topic, situation, perspective}; Declerck → {utterance, situation, perspective, sub n}) live with the respective framework files.

source

inductive Core.Time.Orientation :

Type

The universal vocabulary of orientation times in modern tense theory. See the module docstring for the framework-mapping and citations.

utterance : Orientation
Utterance time (TU / S / t₀). When the utterance is made.
topic : Orientation
Topic time (TT / R). The time about which a claim is made.
situation : Orientation
Situation time (TSit / E / TS / τ(e)). When the situation obtains.
perspective : Orientation
Perspective time (P). What tense locates topic time against — equal to the utterance time in root clauses, shifted in FID and embedded contexts. Also covers Declerck's TO₁ (the binding TO of a domain).
sub (n : Nat) : Orientation
An intermediate TO in a chain. sub 0 = Declerck's TO₂, sub 1 = TO₃, and so on; the index counts outward from perspective.