It seemed like good horse sense to Carolyn and Clarence Gosnell to bring "Joker," an aged gelding, to their 10-acre Potomac spread. The old fella joined "My Horse Spot" and "Spaghetti" in the Gosnell stable, but he had been in the family for 15 years, most recently with their daughter, and it was in a sense a homecoming.

The homecoming became a hassle, however, when a county inspector spied the white-maned newcomer in May. It wasn't that Joker was wild -- he is rather tame and lame, in fact -- but there are rules about such things.

County zoning, it seems, requires at least five acres to house more than two horses. No matter that they had more than enough adjoining tracts to more than meet the requirement -- county maps showed the Gosnell estate consisted of several small adjoining parcels. But the family herd hovered in a barn on a 3.5-acre tract.

"Very honestly, I broke the law, and I got caught," said Gosnell, a real estate developer. To get right with government, Gosnell filed formal documents resubdividing his estate so that one of three lots now measures 5.8 acres. The cost of this bureaucratic exercise: $2,000.

His efforts have now satisfied the county appeals board, which the other day dismissed the inspector's complaint. Later this week, the board is expected to approve a special exception he also needs to keep the horses. "I've asked for four horses this time," Gosnell said, "in case I get a pony for the grandchildren."