One reason for the proliferation of "The Nutcracker" is its tremendous utility, particulary at pre-professional levels. Its box-office popularity keeps many a school and company afloat. The ballet lets everybody - young and old, beginners and polished dancers - get into the act and makes a splendid introduction to the trials and rewards of stage performance.

These functions are illustrated, for example, by the Virginia Ballet Company's version, presented this past week at Woodson High School in Fairfax. It's a home-grown production notable for its charm, taste and expertise.

The Virginia Ballet has sent alumni on to a number of major professional companies, including the New York City Ballet and the Chicago Ballet. The dancing in the troupe's "Nutcracker" reflects the excellence of the training under co-directors Tania Rousseau and Oleg Tupine. And thoug Rousseau's generally skillful choreography is naturally tailored to varying degrees of advancement, at the upper end of the scale there's no lack of technical challenge. The final pas de deux, for instance, includes one-handed hifts, fish divers, multiple pircuettes and eveh Bolshoi-style aerial flips and tusses.

The Maryland Youth Ballet varies the pattern by presenting a holiday confection that isn't "The Nutcracker" but for most purposes might as well be. "The Enchanted Clock," choreographed by Tensia and Peter Fonseca (an MYB graduate now with American Ballet Theater) to music by Shostakowitch and Kabalewsky, comes replete with dancing hollipops, exotic princesses and magic forests. Here again, the decor, the stage craft, the expertly directed mime schemes, the stylishness and self-possession of the dancers, all testify to admirable artistic standards.