Grammatical voice
= Grammatical voice
<Grammatical voice> concerns how a construction relates an event's participants to grammatical positions such as <subject (grammar)> and <object (grammar)>. <Active voice> and <passive voice> provide a familiar contrast, but the categories recognized across <languages> are not limited to that pair.<Universal Dependencies annotation guidelines>[Voice, overview and Act/Pass values]{ref}
In `The mechanic repairs the pump`, the mechanic is the <subject (grammar)>. In `The pump is repaired by the mechanic`, the pump occupies that relation while the mechanic is expressed differently. Both can describe the same repair. Changing `is repaired` to `was repaired` instead changes <grammatical tense> while retaining <passive voice>.
A structural account can therefore hold the participants and event approximately fixed while varying their expression. Separating <grammatical voice>, <grammatical tense> and <thematic roles> prevents a parser or an experiment from treating those dimensions as interchangeable. It also makes the claimed invariants and changes in a comparison explicit.