The list of names to be read at next week's observance of the anniversary of the World Trade Center attack may include people who did not die, and exclude others who did, city officials acknowledged Friday after scrambling to complete the toll in time for the ceremony.

The revised list, with the names of 2,801 dead and missing, shows 18 fewer names than the first comprehensive list made public by the medical examiner last month. Some people reported missing were found alive, suspected fraud cases were discovered and duplications were eliminated.

Even after the revisions, city officials say the list almost certainly contains errors and will likely be fluid long after the anniversary.

"This is not final. This can change -- in fact, I would be surprised if it didn't change," said Ellen Borakove, a spokeswoman for the medical examiner. She added that no changes were expected before the anniversary ceremony.

Listed among the missing until Friday was Sonia Chalco, 30, who on Sept. 11 escaped from the 36th floor of the north tower, where she worked for Kemper Insurance. Unable to reach Chalco the next day, her friend Cynthia Narvaez reported her missing, and because city officials could not locate either woman to prove otherwise, Chalco remained on the list.

"I'm not deceased, obviously ... that's really upsetting," Chalco said when reached by The Associated Press on Wednesday.

Borakove said the corrections made to the list during the past two weeks were in part expedited by reporters for news agencies, including the AP, which investigated questionable cases and asked for clarifications.

"A lot of people gave us information that perhaps we did not have," Borakove said.

Also among the errors discovered in the past two weeks were the names of two men reported missing by families who feared they were near the trade center Sept. 11. One New York man was found at a psychiatric center, and a street vendor who suffered from amnesia was found at a hospital.

The errors discovered on the list recently are representative of the countless snarls in the year-long effort by the police department and medical examiner's office to investigate each trade center missing persons case, which peaked at more than 6,700.

The list released Friday includes victims whose remains have been identified; those presumed dead whose relatives have obtained court-issued death certificates; and about 70 people still classified as missing.

Much of the work to eliminate errors was stalled by the missing cases, when trails ended -- sometimes halfway around the world -- on wrong phone numbers, misspelled names or mixups with foreign consulates.

Some consulates have deleted names from their lists after simply losing contact with relatives. For example, the Malaysian consulate took Gerard Philips off their list after an uncle who reported him missing stopped communicating with the consulate, leading officials there to believe that Philips had been found. He remains on the city's list.

Police Inspector Jeremiah Quinlan, who supervises the missing person investigation, said police have mere scraps of information on some people because they expedited the process of taking missing reports to accommodate thousands of calls.

"This thing wasn't to make it easy for the police, it was to make it easy for the people who suffered the losses," Quinlan said.

City officials also acknowledge the list may exclude some victims who died in the towers. For example, the Mexican, Brazilian and Colombian consulates each report people missing that the city does not include. The city says its information on some of these people is insufficient to keep them on the list for the ceremony.

At the ceremony, former Mayor Rudolph Giuliani will lead the reading of the names, which is to begin and end with moments of silence at 8:46 a.m. -- when the first plane hit -- and just before 10:30 a.m., when the second tower collapsed.