RIYADH, Saudi Arabia (AP) _ Long before there was a crisis in the Persian Gulf, before Saddam Hussein became a universal household name, the American plan for a ground war was in place.

First comes word that it's ''good to go.'' Then seven Army divisions leap forward, veer off in diversion or remain in place - fulfilling their assigned roles in one of 20th century warfare's most intricately constructed battle plans.

For each of the units - two divisions of armor, two of mechanized infantry, two airborne, one cavalry and a host of related combat units - the mission boils down to a single paragraph on a battle order: Commander's Intent.

Within that seemingly narrow framework, however, there is plenty of room for commanders at all levels to improvise, exercise initiative and think for themselves - as long as it does not stray from that simple purpose.

That, say U.S. officers, is the essence of the ''AirLand Battle Doctrine,'' a military philosophy developed by Army brainstormers in the early 1980s to fight the Soviets in Europe, and now about to face its first major test in the Arabian desert.

The doctrine was applied in a limited way in the 1989 invasion of Panama, but that was nothing compared to the showdown in the desert.

While primarily an Army-plus-Air Force concept, in Operation Desert Storm it also encompasses two Marine divisions along the Saudi Kuwait border, six Navy carriers and offshore striking power, more Marines primed for a classic beach landing from the Persian Gulf, and troops of half a dozen major partners in the multinational coalition.

''AirLand Battle is sort of a play in three parts, all on stage at the same time,'' one senior officer said.

It is intended to make maximum use of the weaponry that has come into the American battle inventory in the past decade - night vision equipment, missile-firing jets and helicopters, ''smart'' weapons that can take out a single objective, ''area denial'' munitions that keep the enemy from his own resources, laser-guided tank and artillery guns, radar-linked weapons that identify, ''prioritize'' and destroy enemy threats almost as they are mounted.

AirLand Battle also was designed originally to deal with superior numbers - the Soviets - and ''make use of every asset we have available, to fight at longer range with better controls,'' said an officer who has studied and taught the doctrine for several years.

While the steady attrition of Iraqi tanks and artillery by U.S. air power has undoubtedly shifted the numerical odds, the concept still has application because the Iraqis fight according to Soviet doctrine.

''Theirs is not as fluid, commanders are not normally given as much flexibility as we have. They have very little flexibility as to what they can do,'' said the officer. The scenario for AirLand battle in the desert, officers said, could go like this:

As U.S. tanks and artillery engage the Iraqis at close range and seek to blast through their layered defenses, tactical aircraft, long-range missiles and perhaps even paratroops strike at targets well into the Iraqis' rear, inflicting casualties, sowing confusion and disrupting their capacity to react.

A third element of U.S. forces remains well back to guard against any bold attempt by the Iraqis to infiltrate the American rear and do the same thing.

All this is orchestrated by senior officers operating from command posts farther forward than in any previous battle system, planners say. The senior Army commander, in fact, will have control of the Air Force and Navy planes as well as his own aircraft, whether they are hitting targets close to his position or many miles beyond it.

One key tenet of the doctrine is ''agility,'' defined as thinking and acting faster than the enemy. Another is ''synchronization,'' or concentrating all assets - ground and air - on a specific target at the same time.

While strategists concede that such things as a lack of terrain features may make it harder to coordinate forces and fix positions in a rapidly moving assault against the dug-in Iraqi forces in Kuwait, they say the method has been well-tested in a desert environment.

''Everybody who's in any way involved has trained at Ft. Irwin,'' said one officer, referring to the California training center where American troops learn desert warfare.

Moreover, he said, bi-annual U.S.-Egyptian maneuvers in the Egyptian desert, called ''Bright Star,'' have enabled U.S. forces to further hone their skills in the desert.

Despite six months of open preparation for war, U.S. planners said, in interviews before the ground offensive began, that they were confident of maintaining the ''tactical surprise'' needed to catch the Iraqis off balance.

''We had it when the air war began and we'll have it when the ground war begins,'' said one officer. ''People may think they know where all this is coming from, but they don't.''

What could stop it?

''Having so much equipment that we couldn't handle it, and better equipment,'' he said.

Another officer said the Iraqis were never in such a position, and weeks of bombardment had not helped them.

But for all its carefully developed written concents and football-style diagrams, the AirLand expert said, the doctrine pays homage to one implacable reality of warfare: Once the first shots are fired, the best-laid plans may go out the window.