AFTER THE WORST WEEK ever at the gas lines, Washington area motorists are battle-weary and anxious for relief - and finally the governors of Maryland and Virginia and the mayor of the District have begun to respond in a coordinated fashion. The result will not be more gasoline for sale, but it may mean more order in the way the limited supplies are sold. That, after all, has been the heart of the problem; most people are prepared to accept shortages, but they do want to know when and where they can expect a fair shot at the pump for their share. Governors Hughes and Dalton and Mayor Barry have now taken a necessary first step by requiring minimum purchases as a way to discourage "topping off."

Will these orders - requiring minimum $5 and $7 purchases and prohibiting sales of more than two gallons in containers-end the long lines? Many gasoline station owners report that topping off hasn't been that widespread a practice in the last few days. Nevertheless, the new sanctions should help prevent a resurgence of this form of hoarding.

Another source of trouble - the totally unpredictable and terribly brief sales hours at pumps - also is being addressed by city and state officials. Maryland and the District are working on plans to distribute more of their total supplies to dealers who agree to stay open certain evening and Sunday hours. In Virginia, dealers have been ordered to work out a timetable "to assure the maximum number of stations possible are open at any one time" in the jurisdictions of this region. Again, spreading out the sales hours won't produce more gasoline to sell, but it should help people plan their purchases. In addition, station owners should make every effort to calculate the number of hours they can pump and then post these times on large, easily visible signs.

What else should area officials do? The next step to be considered at a meeting of the mayor and two governors here tomorrow is the possible use of odd - evenlicense number allocations. Now that the other steps have been taken, the odd - even rule should be tried - not adopted irrevocably and forever, but tried to see if it works.At the very least, it would cut in half the number of cars eligible to get in line each day. In California, where the system is in effect, it is said to have worked fairly well - so long as it has been accompanied by requirements that a certain number of gas stations stay open on weekends.

With the minimum purchase and better sales hours, the odd-even system deserves a test here. It is simple, it can be put into effect immediately and it requires no elaborate paperwork or bureaucracy. The reluctance of officials to issue too many complex orders is understandable, but a few basic ground rules could give everyone a more reasonable opportunity to plan purchases and uses of the limited supplies available.