An article in Friday's editions of The Washington Post incorrectly reported that a new Virginia law prohibiting mandatory timed message telephone service statewide would not apply to Northern Virginia. Actually, businesses in Northern Virginia now pay a flat unit message rate and are charged extra after the first 50 local calls. That service would not be affected by the new law, but Northern Virginia business and residential telephone customers would be covered under the prohibition against charging for the length of local calls.

With Virginia legislators set to return to Richmond tomorrow for an unusual "clean-up and veto session." Gov. Jahn N. Dalton yesterday signed into law a measure that prohibits telephone companies from forcing timed message rates on their customers.

The phone bill, overwhelmingly approved by the General Assembly, was among several controversial pieces of legislation that the Republican governor must either sign or veto by midnight tomorrow. Dalton yesterday reviewed various measures and heard the groups supporting or opposing them.

Dalton has not vetoed any bills this week but is expected to oppose some measures. The bills would automatically become law unless vetoed by the governor. In its session tomorrow, the Democratic-controlled assembly can try to override any gubernatorial veto by a two-third vote in each house.

"The governor has promised to tell us by 10 a.m. Saturday which bills he intends to veto," said Senate majority Leader Adelard L. Brault (D-Fairfax), who estimated that tomorrow's final assembly session will be able to adjourn by early afternoon.

The phone measure, sponsored by Del. Richard L. Saslaw (D-Fairfax), was strongly opposed by the Chesapeake and Potomac Telephone Co. C&P had sought authority from the State Corporation Commission to institute state-wide timed message service for businesses similar to that already in effect for businesses in Northern Virginia.

The telephone company had proposed making such charges mandatory for all businesses but withdrew the request after Saslaw's bill neared passage. It can continue the charges in Northern Virginia since the new law does not affect the charges there.

Another Saslaw bill that had been considered vulnerable to a veto by Dalton will apparently be signed after some amendments are added, according to a lobbyist source. The measure would prevent major oil firms from establishing company-owned gasoline stations within a mile and a half of independently operated stations.

Dalton met Wednesday with a group of independent gasoline retailers who support the bill and then heard yesterday from representatives of oil firms who oppose the legislation.

"The governor is hearing one group from each side," said a Dalton aide.

Brault said Dalton has assured him that he will sign a Brault bill requiring the state to pay for recount costs in close elections. But the governor has asked the Fairfax lawmaker to draft some technical amendments to the measure.

Brault said Dalton is expected to veto a bill that would remove highway condemnation legal work from Republican Attorney General Marshall Coleman's patronage appointees and give it to full-time city and county attorneys.