A threatened strike by unionized D.C. public school custodians, bus drivers and cafeteria and maintenance workers was postponed yesterday until Jan. 31 at the earliest pending a court decision on whether such a work stoppage is legal.

School Superintendent Arlene Ackerman secured a 10-day temporary restraining order in D.C. Superior Court forbidding Teamsters Locals 639 and 730 to stage a threatened strike on Monday. A hearing on the issue was scheduled for Thursday before Judge Joan Zeldon.

The school employees--who carry out such essential functions as serving lunch, stoking boilers, and cleaning and repairing buildings--are seeking bonuses and raises comparable to those received by their counterparts in other city agencies in the last three years.

The workers contend that they are allowed to strike because their contract expired in 1996. Union members voted overwhelmingly last Sunday to strike if their pay proposals were not met by yesterday.

But schools general counsel Veleter Mazyck said a strike would be illegal because the unions are working under what is known as a "rollover contract"--meaning it continues as long as the union does not give "sufficient" notice that it wants to open negotiations for a new contract. The two sides disagree on whether the Teamsters gave such notice.

Ackerman and other city leaders say they want to find money to fund $1,700 bonuses for the employees, to match those given other city workers late last year. But they say they currently cannot afford the workers' other proposals: raises of 3.7 percent and 3.8 percent that other city employees received in 1998 and 1999. Those issues, city officials say, can be addressed only as part of negotiations for a 1999-2003 contract.

"We do appreciate all the fine work all our staff members give each day. We do want to pay them well," Ackerman told the Board of Education this week. "But . . . we can't meet these demands even if we wanted to."

Before yesterday's court developments, Ackerman had arranged for substitute lunches and other emergency measures in case of a strike.

Ackerman sent a memo to employees saying they would be fired if they were absent Monday without authorization. She also wrote a letter to parents summarizing her version of the dispute and canceling most academic and all athletic activities planned for this weekend so the staff could spend the time preparing to open the schools on Monday if a strike occurred.

CAPTION: Superintendent Arlene Ackerman said the District schools cannot afford to pay the raises sought by drivers, custodians and cafeteria workers.