The relationship between the Postal Service and the Postal Rate Commission has always been a stormy one, but in recent weeks it has taken a bizarre new twist.

The latest squabble unfolded when Elliot H. Rock, an executive assistant with the rate commission, asked the Postal Service to turn over a report that was potentially embarrassing to the service.

When the agency refused, he asked for the same document as a private citizen by invoking the Freedom of Information Act (FOIA), the law often used by journalists, lawyers and others to gain access to government files.

Of course, the ploy did not fool Postal Service officials, who responded that even private citizen Rock could not see the report because it was an internal document, not meant for public consumption.

Rock appealed, again citing FOIA regulations that say "factual" information cannot be withheld. But the response to the appeal, this time from the Postal Service's general counsel's office, was more to the point: Rock could not see the report because the report does not exist.

Why all this confusion? According to Charles D. Hawley, an assistant general counsel for the Postal Service, because the report has not been completed, it is not officially a report. In his letter to Rock, Hawley said, "We cannot at this time release any portions of the report you want, whether factual or not, because it does not yet exist."

Hawley said his decision was "without prejudice to your right to renew your request on any grounds you choose once the report comes into existence." If Rock did not like it, Hawley said, he could take the Postal Service to court in any federal district court "in which the report would be kept if it existed."

All well and good -- or at least until parts of the "nonexistent" report found their way into the July 8 edition of Business Mailers Review, a trade newsletter for Postal Service watchers.

According to the newsletter, the report knocks the wind out of the Postal Service's figures on its productivity gains. While the Postal Service was claiming yearly gross labor productivity gains of 4.5 percent -- claims it took to the bargaining table in its labor negotiations -- the report by a Texas research firm shows that, on average, productivity had been increasing by a paltry 0.8 percent a year.

Productivity gains -- essentially the increase in the volume of mail handled by the same number of postal workers each year -- had been the hallmark of former postmaster general William F. Bolger's tenure. But many observers, including some Bolger critics, were skeptical of the figures, saying that the increase in mail volume was offset by a decrease in the average size of each item mailed.

The Texas economists apparently factored in the weight of postal items to deflate the Postal Service's official productivity figures. Now postal officials have said the Texas report is merely one of several pending productivity studies. In other words, they do not want to release it.

"As I understand it, the report that they were after was part of a series of reports we had contracted out for," said Martha Smith, the Postal Service's acting records officer. "There are provisions under the Freedom of Information Act which allow us to withhold some information."

But a more-recent July 17 letter from Hawley to Rock shows that the Postal Service may be willing to give in. Hawley said he made his decision after making "certain inquiries." But he said, "It now appears that our inquiries may have been misunderstood" and he is formally reopening Rock's FOIA appeal.