Government exhibit 1951, yet another embarrassing Microsoft Corp. electronic-mail message, would barely have attracted attention when it was introduced at the company's antitrust trial yesterday had it not been for the date it was sent: Jan. 5, 1999.

By then, the government already had spent three months bashing the firm in a Washington courtroom with its internal e-mails, leading observers to expect that the software giant would become more circumspect in its electronic communications.

Apparently not.

Worried that the government's chief economics expert was going to present data about a drop in the market share of Netscape Communications Corp.'s Internet browser, a Microsoft public relations manager urgently asked other employees in the e-mail if they had any research reports that might show otherwise, which he wanted to use to attempt to influence reporters covering the trial.

"What data can we find right away that shows Netscape browser share is still healthy," the manager, Greg Shaw, wrote. "It would help if you could send me some reports showing their market share healthy and holding. This is for press purposes."

A product manager, Robert Bennett, wrote back that "all of the analysts have pretty much come to the same conclusion, which is that [Netscape's] share is declining and [Microsoft's] is gaining."

"I don't want to be proactively telling people that [Netscape's] share is doing well," Bennett continued. "We are winning [because] we have better technology -- if we show them maintaining/gaining share then we contradict that point."

As the messages were read aloud yesterday by government attorney David Boies, the federal judge presiding over the non-jury case, Thomas Penfield Jackson, laughed.

The expert whose testimony was the subject of Shaw's worries, Massachusetts Institute of Technology professor Franklin M. Fisher, was back in court yesterday as a rebuttal witness for the government. Asked to comment on the message, he said simply, "This document speaks for itself louder than most."

Shaw's e-mail was among several boxes of documents recently provided to government lawyers. Although defendants are not usually required to turn over documents after a trial begins, the judge allowed both sides to conduct additional "discovery" in light of America Online Inc.'s $10 billion acquisition of Netscape.

Fisher argued in January -- and again this week -- that Netscape's share of the browser market plummeted because of Microsoft's anti-competitive conduct, specifically the company's decision to include its Internet Explorer browser in its dominant Windows operating system. The government contends that the inclusion of Explorer in Windows gives Microsoft an unfair advantage over Netscape -- one that violates antitrust laws.

In its defense, Microsoft has been arguing that Netscape wasn't crippled by Microsoft and still has many ways to distribute its browser. That contention would be helped by studies that show a "healthy and holding" market share for Netscape.

Government lawyers plan to call International Business Machines Corp. executive Garry Norris on Monday. He will allege that Microsoft charged IBM more to license copies of Windows because IBM was selling a rival operating system.