doing the duties of another person for a limited time

substituting in a role

temporary (while more information is prepared, more supplies are obtained etc); during the period of time in-between

temporary

during the time between (e.g. while waiting)

at the same time

(Latin: pro tempore) for the time being

temporary

lasting for, designed to be used for, a limited time only

lasting only a short while

made or done as a trial, to test the effect

conditional, experimental