In one particular airline, their BARO REF is set to STD when cleared to a Flight Level and QNH when cleared to an altitude, provided altitude restrictions for SIDS/STARS are complied with and MSA is attained on a climbed. Having the Transition altitude set in the approach page is for reminder only. When there's a request from ATC for altitude/level passing, QNE or QNH is momentarily set for the reply only.