mõõtevahendi kasutustingimused, kus mõõtesuuruse muutus ajas on selline, et suhe mõõtevahendi sisend- ja väljundsignaali vahel ei ole oluliselt erinev võrreldes olukorraga, kui mõõtesuurus on ajaliselt püsiv, operating condition of a measuring instrument or measuring system in which the relation established by calibration remains valid even for a measurand varying with time, mõõtevahendi või mõõtesüsteemi kasutustingimused, milles kalibreerimisel kindlaks tehtud seos kehtib ka aja jooksul muutuva mõõtesuuruse korral, operating condition of a measuring instrument or measuring system in which the relation established by calibration remains valid even for a measurand varying with time, operating conditions of a measuring device in wich the variation of the measurand with the time is such that the relation between the input and output signals of the instruments does not suffer a significant change with respect to the relation obtaining when the measurand is constant in time