Latin tenses in commands (semantics)

From a semantic perspective, a tense is a temporal circumstance in which an event takes place relative to a given point in time. It is absolute (primary) if it relates the represented event to the time of the speech event and it is relative if it relates the represented event to the time of another event in the context of discourse. In turn, a relative tense may be “relative to absolute” (secondary) if it relates the represented event to the primary tense. Read more about possible tenses in the article on grammatical tense.

Imperative clauses represent actions to be carried out (read more on Imperative mood). While indicated events are placed in a timeline relative to the speech act (future, present, past), requested actions can be carried out only after the speech act, therefore imperative clauses do not vary in primary tense, the requested actions being always future. However, a task execution can be placed in a temporal circumstance relative to another event -- after, while or before that event -- which means imperative clauses may carry a secondary tense.