Whoa! Can that have been the young Mozart who walked out on the stage of the Temple Square Assembly Hall Saturday to take his place at the keyboard? Or was it 13-year-old Janae Codner, opting, Cherubino-like, to open this evening of Mozart piano concertos in 18th-century male dress?

If the latter, then maybe we should find out where she gets her costumes made and send one to all the other pianists on this series. Because between now and November, the square is presenting no fewer than 30 of them in a nine-month survey of all the Mozart piano concertos, with the K. 382 and 386 Rondos thrown in for good measure.That's a lot of pianists. But mark my word, they will be doing well to come up to Codner's standard. For this was as professional an account of the Concerto No. 22 in E flat major, K. 482, as one could hope for soloistically.

Witness the beautifully shaped first movement, confident in its accelerations yet withal lyrical and elegant, even when the pianist chose to bear down harder in the central pages. Likewise the Andante, a bit calculated in its flow but admirably articulated down to the smallest detail. After which the opening of the finale tripped along purposefully, with some especially attractive shadings the second time around.

Not that the other young soloists on this program did not acquit themselves honorably. In the Concerto No. 16 in D major, K. 451, for example, the University of Utah's Collette Call may not always have known what to do when the music got slow - to wit, her prosaic account of the second movement. But in her hands the opening movement had a thrusting momentum, and happily the finale found her back up to speed, in more ways than one. I do wish she would not back off phrase endings so gingerly, though - at times it damages the line.

If anything, her U. of U. colleague Monte Caldwell brought even more sparkle to the Concerto No. 21 in C major, K. 467 - thanks to the movies, probably the most popular of any of the Mozart concertos.

Certainly his animated approach to the opening Allegro maestoso made it sit up smartly, even a bit abruptly in places. But it was hard not to admire his dynamism, or the sweep he found in the development. And if the slow movement verged a little on the dreamy, with a fair amount of pedaling, it was nonetheless well-controlled, followed by a finale whose fire and dash found the pianist always where he was supposed to be.

That cannot be said of the BYU Chamber Orchestra under David Dalton, which actually got off at one point. By the same token their otherwise vigorous accompaniments were often compromised by variable intonation, mostly in the winds, and a general lack of refinement.

Too much to expect from a student orchestra? Maybe. On the other hand, Mozart himself was scarcely much older than this when he wrote some of these concertos. And, as the three soloists reminded us, youth need not be a handicap even if one isn't Mozart - or even a costumed facsimile.

Upcoming concerts are scheduled April 19, May 24, June 15, July 12, Aug. 3, Sept. 21, Oct. 19 and Nov. 16. Soloists will include Jed Moss, Kimberly Crosby, Mira Gill, Melanie Massey, Jennie Watson, Bonnie Gritton, Susan Duehlmeier, Del Parkinson, Jeff Manookian, Marjorie Janove, James Margetts, Dustin Gledhill, Janet Mann and Jeffrey Shumway. Starting time for each is 7:30 p.m. and admission is free.

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