Yes, "International Velvet" is a terrible sequel. It stands out in a year of terrible movie sequels for the special crime of taking a character that many people love and twice betraying her.

The character was 14-year-old Velvet Brown, as portrayed by the 12-year-old Elizabeth Taylor in the 1944 film "National Velvet," an earnest young horsewoman who rode her horse, "Pie," to victory in the Grand National, only to have the prize taken away from her because only males are allowed to complete. In this film, we have the grown Velvet, who should be 48 now; her horse, Pie, who should be dead now, but is shown just retiring from the stud business; and the new team of her niece, Sarah Velvet Brown, and Pie's foal, Arizona Pie.

It is hard to decide who is more thoroughly charmless in this film, Velvet Sr., as played by Nanette Newman after Elizabeth Taylor refused to have anything to do with the project, or S. Velvet Jr., as played by Tatum O'Neal.

The story line is that Velvet has turned into an aimless has-been, living with a man who still talks about "hangups," and herself even to saying, at crisis time, things like "No news is good news!" and "It'll be all right!" The niece is a sullen and homely girl, thoroughly uninterested in people.

But wait. There is a value and interest in this film if you can separate it from its unattractive characters and past associations. There is a kind of reverse "Turning Point" here, where the woman of the post has ruined both career and marriage, but the younger one is seen as approaching both with less sentiment but more sense.

The elder Velvet murmurs cliches about "peaking too soon" in here horsemanship and "doing the things one does when one wants to hurt someone" in the marriage that preceded the present arrangement. The young Sarah learns discipline and how to swallow her own vanity as she undergoes rigorous training for the Olympics, and, with a minimum of courtship, chooses as a suitable husband the silver-medal winner, since she has the gold herself.

It is, perhaps, the difference between the aunt's sport, racing, with its quick glory or defeat, and the niece's, the three-day event, demanding a variety of skills and endurance. What is shown of dressage, cross-country and show jumping - unfortunately, with the beauty often eclipsed by close-up shots of sweating faces, the same stupid editing as done in ballet films - is an excellent lecture on the rigors of doing something demanding and doing it well. Sarah triumphs (as how can she not, being the only Olympic contestant who has background music during her efforts?), but a large part of her training is the ability to accept setbacks and to defer her ambitions to the team's.

One goes away feeling that she and her Olympic champion husband will make a life that will satisfy themselves, even if they fail to charm others. Princess Anne and Captain Mark Phillips have, after all, earned respect in the sport, even if they haven't spread enchantment.