City negotiators have nearly completed an agreement with District Cablevision Inc., the firm selected by the City Council to receive the District's cable television franchise, that would allow the cable firm hold back on some promised services until a demand for them arises.

A proposed agreement could be sent to the City Council for approval as early as Nov. 1, Richard Maulsby, executive director of the city's cable office and a member of the negotiating team, told the council's cable committee yesterday.

Under the agreement being negotiated, the city would still be in a position to get the system District Cablevision promised but the timetable would be changed.

Maulsby said in an interview that he is satisfied the city will get more than it requested in its bid specifications.

Robert L. Johnson, president of District Cablevision, said the agreement would allow his firm to save money at the outset by implementing parts of its proposal based on "trigger mechanisms."

The cable firm promised to build simultaneously a 78-channel residential cable network and a second residential (shadow) cable that would be activated at a later date. The proposed agreement would require District Cablevision to construct the second cable only when there is a demand for added channel capacity.

The firm promised to activate a separate institutional network. The proposed agreement would delay activation of the network until there is a demand for it or until some specified date, whichever comes first.

The firm made financial commitments to public acccess and community services. But the agreement would allow the firm to delay some of those commitments until the cable system received a designated number of subscribers.

Maulsby and Johnson stressed that negotiations are continuing and would not reveal other details. Maulsby did acknowledge that the city is discussing a security fund in excess of $1 million to be used if the cable firm defaults. Johnson would say only that the amount under discussion is "a bit heavy-handed."

The latest progress report marks a major shift in negotiations. Last month, some City Council members were annoyed when Maulsby reported that District Cablevision had proposed changes that would substantially alter the cable system it had orginally proposed.

Johnson said that his company will still provide everything that it promised. "We've got to be healthy as a company to provide the public benefits, and the trigger mechanisms allow us to do that," Johnson said.

Meanwhile, District Cablevision's business partner, Chesapeake & Potomac Telephone Co., must still receive federal approval to build the system for District Cablevision.

C&P has requested permission from the Federal Communications Commission to construct a cable system in an area in which it also provides telephone service.

Meanwhile, Capital City Cable, a firm that also competed for the District franchise, asked the Justice Department to investigate C&P's cable involvement. Maulsby said that C&P received a letter from the Justice Department and has been given 20 days to respond.