You're a jogger, barrelling flat out along a trail in Rock Creek Park, deep into the Zen of it all. Suddenly, you round a curve and what should loom ahead but the backside of a horse, so broad it spreads across the whole trail. You want to pass.

Running etiquette requires that you:

A - Whinny like Mr. Ed and gallop on by;

B - Whap the animal in the haunches with a birch switch to clear the path;

C - Scream "TRACK!" and curse the rider, warning that the next time the four-legged creature breaks your stride, he'll be sorry;

D - Halt and nibble on a carrot until the horse turns off;

E - Slow down, ask if you may pass, give the rider a chance to get the horse under control and ease on by.

Riders would consider you a saint if you picked D or E, for all manner of base behavior has been known to occur when man meets beast deep inside the forest. A spooked horse, a thrown rider, a jogger KOed with a swift kick to the chops . . . All manner of conflagration can result, warn riders who have fought hard to rein in nervous horses from such encounters.

Among a rider's worst enemies are the dogs of runners - canines allowed to roam free enough to express their innermost selves by yapping wildly at a horse's hindmost. Such freedom can easily spell disaster, though inquiries to the proper officials failed to turn up any lawsuits resulting from any run-ins.

Several runners and riders said they didn't mind sharing their space with each other; some even espoused the possibility for peaceful coexistence. Each argued for his team's advantage underfoot, but only one official suggested any definitive rules of the roads.

"On the trail, a horse always has the right of way," says Rock Creek Park Superintendant Jim Redmond. "It's just common courtesy. A jogger or pedestrian can always come to a halt, a horse is harder to maneuver. It's a big animal and few [joggers] know how tough their personal life can get. Some are very nervous, flighty, sensitive."

The weight of tradition is on the horse's side, since jogging was not the national pastime back in 1890, when 15 miles of Rock Creek Park trails were legislated for equestrian sport. But a wave of jogging enthusiasts has changed all that, and cars spouting noxious exhaust fumes have chased them from the roadways into the forest, playing havoc with history.

What it boils down to is common sense, says Redmond. "If a horse is galloping, you get out of the way."

"There's plenty of room for all of us," says one veteran Rock Creek equestrian, who regularly mounts a 14-year-old mare named Daisy and grumps about the "appalling lack of courtesy" that runners, cyclists and drivers seem to reserve for riders and each other.

"I almost faint when a driver stops to let me cross the road," she says, such is the swerving and honking that goes on at the sight of a horse.

What really scares the animal, though, are sunbathers who lie about on blankets looking like dead people, or runners who lurk motionless behind trees. Sometimes, Saisy just doesn't know what to think.

"I always speak to people in the woods," she says. "Not because I'm friendly, but just so Daisy will know you they're not trees. A tree suddenly come to life can really frighten a horse. People just don't act normal sometimes."

Which, of course, is understandable to the jogger who rounds a bend and runs into an ominous Rock Creek Cavalry. A horse hoisting a menacing tail can make a runner anxious, too, and, for the serious runner, breaking one's stride is among life's true unpleasantries.

"There needs to be a lot more consideration on both sides," says Mary Taylor, manager of Meadowbrook Stable. She pleads for a middle ground: If a rider plans to walk old Ned, he should move over and let a runner pass; if a runner cannot maintain a gallop, he should step aside for the horse.

As for the right-of-way dilemma, well, it also extends to pedestrians and joggers who tread the bicycle paths. What rights do the cyclists have? Not exclusive ones, says Redmond. "Bike paths are like the roads - the pedestrian has the right of way."

Consider the daring cyclists who barrel down hills like banshees, disregarding what's around the next bend. A jogger or weekend wanderer can hardly be expected to jump out of the way of a speeding bullet. And there have been a handful of serious collisions, says Redmond, ussually head-ons between bikers. He urges slowpokes to keep to the right.

Still, there are bound to be misunderstandings, and occasional outbursts of vigilante spirit. One jogger leers maliciously at how he evens the score with bikers who scoff at pedestrians and race down the hills shouting, "Outta the way!"

"I carry a sawed-off broom handle," he says. "You can't imagine the havoc it plays on the spokes of a bike going 30 mph." way back home.

Goose-hunting on the Eastern Shore is the best goose-hu