A Nov. 3 referendum on an educational tax credit initiative was thrown into uncertainty yesterday when the entire nine-member D.C. Court of Appeals agreed to hold a hearing on the measure and suspended an order by a three-judge panel that had put the question on the city ballot.

The full court said it would hear the case next Tuesday. Although the court gave no indication when it would decide the matter, lawyers for both sides said they expected a ruling in time to put the measure on the ballot, if the court approves it.

Officials of the D.C. Board of Elections, which earlier had barred the referendum, said that because of the city's computerized voting system it only needs to be told by the court by Nov. 2 in order for the question to appear on the ballot the next day. However, if there is no ruling by then, there would be no referendum on Nov. 3, election officials said.

"I'm happy that the full court is going to consider the matter," said Albert J. Beveridge III, the elections board chairman. "We believe this is the most important issue to come before the board since the elections board was established."

H. Richard Mayberry, lawyer for the tax credit proponents, who collected more than 27,000 signatures in their petition drive, said his group would continue its campaign despite the uncertainty.

"I'm confident that the entire court will uphold the right of the initiative to appear on the ballot just as the three-judge panel did on a 2-to-1 vote ," Mayberry declared. "We met the required number of signatures and the ward distribution. Therefore, it should be on the ballot."

In early August, the Board of Elections ruled that 82 percent of the signatures had been collected by out-of-towners who were not properly registered D.C. voters, and refused to approve the referendum.

However, on Sept. 18 the three-judge panel -- Frank Q. Nebeker and Stanley S. Harris, with Julia Cooper Mack dissenting -- ordered the referendum to be held. Yesterday's decision to suspend the three-judge panel's ruling and hold a full-court hearing was made by a majority of the court. No vote was announced.

White House and Justice Department officials have since decided to name Harris the U.S. attorney here, making it uncertain whether he will participate in the new hearing.

Under the proposal, taxpayers would be allowed to deduct up to $1,200 per pupil from D.C. income taxes for expenses at either private or public schools.

The measure has been sponsored by the D.C. Committee for Improved Education, an offshoot of the National Taxpayers Union. It has been strongly opposed by a wide array of city and public school officials who argue that it will take large sums from the city treasury and harm D.C. public schools.

The proponents, who collected almost twice as many signatures as required by law, say the measure will upgrade education by giving parents more choice in their children's schooling.