They call it the Doomsday Book, a thick, graph-laden report prepared by Prince George's County budget analysts last fall that plots the county's fiscal health over the next five years.

The prognosis is not good: The report shows the county going broke if a number of escape hatches--an improved national economy, more state aid, voter modification of TRIM, a new $10.5 million business tax or employe willingness to forgo wage increases--were to fall through.

Its numbers conjure up a half-empty county government building in Upper Marlboro whose employes supervise only the most basic fire, police and school services.

County department heads and politicians say the admittedly worst-case situation would mean:

* Schools eliminating most courses outside those mandated by the state for high school diploma requirements or by the federal government. Most languages, instrumental classes, and advanced classes would be dropped. Classroom size, already higher than other area jurisdictions, would rise still further, approaching 40 students per class. Students, who already pay many fees, might have to pay for textbooks and laboratory time.

(There is some sentiment among the county Board of Education members to consider such fees when they reconvene next month, even though further cuts in education, county officials and business leaders say, would hurt efforts to bring high-priced development to the county.)

* The police department would be forced to focus all its energy on situations where either life or property is threatened, getting rid of foot patrols, some stakeout squads and burglary investigation programs.

"Barking dogs, loud radios, loud parties. Obviously we could reach the point where we'd have to tell the public, 'Sorry we don't do that anymore,' " said Police Chief John E. McHale Jr.

* Workers in all county departments would face layoffs. Without the small amount of additional state aid received this year, Glendening said he would have been forced to get rid of 60 policemen.

* Road maintenance, grass cutting and snow plowing would occur only on the main arteries; curb repair would likely end.

* Library hours would be reduced and some branches might be closed. At the same time the Parks Commssion, which levies a separate tax, might have to begin administering some services that the county government could no longer afford.

* The bond rating would likely plummet--it has already dropped from AA to A-1 in one rating house--forcing the county to pay higher interest rates if it wants to float bonds for new buildings, roads, a jail. But because the county cannot afford higher interest rates, those projects, already slowed by TRIM, would be suspended indefinitely or would have to be paid for by taking money from programs in the county budget.

* The disparity between poorer residents who rely on county services and those who can afford private swim clubs, schools and home libraries would widen. There would also be a growing gap between those who live in the county's 28 incorporated towns, where many services are provided, and those who don't.