In the listing of vehicles exempt from the Washington area's odd-even gasoline sales plan published in yesterday's editions, van pool vehicles were described incorrectly as exempt only if they are driven a certain minimum number of miles per day or week. There is no minimum mileage for van pools in the plan.

Here are the rules governing the sale of gasoline under the odd-even plan that went into effect today in the Washington area:

Gas stations will display flags showing the availability of fuel for eligible vehicles red means no gas; green means all grades of gas are available; yellow means leaded gas only available.

Vehicles with license plates ending with an even number, including zero, can buy gasoline on even-numbered weekdays of the month.

Vehicles with license plates ending in an odd number can buy gasoline an odd-numbered days of the month.

Cars with personalized tags, or tags having only letters, follow the rules for even-numbered tags.

Out-of-state cars, not bearing D.C., Maryland or Virginia plates, can buy gasoline any day.

Saturdays, Sundays, Holidays and the 31st of each month are 'open' days when anyone who can find it can buy gas.

In addition to cars with out-of-state tags, a number of other exemptions are included in the order, but no exempt vehicle will be entitled to move to the head of any line.

Minimum purchase rules continue. In Virgina and the District the minimum sale is $5 regardless of the size of the vehicle or its tank. In Maryland, minimum sale for cars with six cylinders or more is $7; for those with four cylinders, $5; no minimum purchase for cars with tanks that hold eight gallons or less. Each jurisdiction allows a maximum purchase of two gallons for shortage cans.

Areas included in the plans are: all of the District; all of Maryland; in Virginia, Arlington, Fairfax, Loudoun and Prince William counties and the cities of Alexandria, Falls Church, Fairfax Manassas and Manassas Park.

In addition to vehicles with tags other than the District, Maryland and Virginia, a number of other vehicles within the affected jurisdictions are exempt. They include: emergency vehicles, such as ambulances; mopeds, motorized bicycles and motorcyles; official funeral vehicles, but not cars that are part of a funeral procession; any vehicle operated by a physician or nurse (the operator must show his or her professional license at the pump); any bus or school bus; taxicabs and marine craft (although cabs will be encouraged to use special depots located around the city); public transportation vehicles; vehicles with commercial tags; construction and agricultural equipment; vans used for car pooling with official tags for those purposes (B tags in the District, VP in Maryland and Virginia); other vans used for pooling with the official sanction of the employing firm; persons who must drive 75 miles a day, or 400 miles a week, in the course of their work, exclusive of commuting.