The rigors of recession may not have done much for the profits and pleasures of American corporate life, but they appear to have worked wonders in the character department.

For the startling new theme at the top this year is, of all things, modesty.That's the uncharacteristic thread running through the latest batch of annual reports surveyed for this column by William P. Dunk, a leading national authority on corporate communications, based in New York and Dallas.

Once a year, Dunk gives us his exclusive annual report on annual reports, and it repeatedly has kept us ahead of such major changes as the trend toward slimming down and reducing debt.

Now, though, comes a grim ac-knowledgment that the slogans in the executive "success" books were not enough: a "mixed and muted" message that "much remains to be done" - and that it will have to be done by, of all people, the corporation's own employees.

"We can say that the annual report is undergoing a critical transformation," Dunk told me. "In more thoughtful major corporations at least, it is no longer a cheerleader document directed at investors and other external constituencies. Its most important audience is the corporation's own employees.

"In the 1980s the corporation underwent restructuring; in the 1990s it will be undergoing complete reconstruction. The report is no longer a vehicle for celebrating good results or for rationalizing mediocre performance. It is a continuous explication of what must be done to ensure it has a future. It is a vehicle for dispensing the gospel of continuous improvement - and disposing of complacency."

The main theme of General Electric chairman John F. Welch Jr.'s annual-report letter, for example, is a "workout process" emphasizing employee self-improvement to produce products faster and cheaper.

And IBM chairman John F. Akers not only takes a notably measured tone in warning of the need for "continued prudence," while "much remains to be done," but does so in an equally subdued and sober graphic environment. "In the 1950s," Dunk noted, "IBM practically invented the modern annual report: lots of big pictures, very little type and minimal disclosure. Now IBM is clearly reinventing its report. The 1990 report has only four major color photos, each taking up less than half a page; this is a copy-heavy report." ("If Akers has got it right," Dunk added, "we should look in reports for the company that is performing well but running twice as scared as last year.")

Similar sobriety runs through many other reports, Dunk said, as companies emphasize the need to get a tight grip on operations, "since it's become so hard to raise revenues or to raise capital in the markets of the 1990s."

Lillian Vernon speaks of "greater operational effectiveness and better inventory management." Loral has "improved productivity" in almost every division, "increasing by one-third the average sales per employee since 1988." CIGNA, which used to speak of strategies, now focuses on implementation.

And, Dunk reported, "everybody is into speed of delivery (General Mills), more personnel cuts (Digital Equipment), globalization (W.R. Grace and Procter & Gamble), empowerment, strategic alliances - and a host of other tactics for doing more, hopefully better, for less."

A key euphemism for this new emphasis is "operational," as in Var-ian's call for "operational excellence" through "an all-consuming customer focus, unbending commitment to quality, flexible and responsive factories, faster time to market, and organizational excellence."

If all this is a far cry from the throw-your-hats-in-the-air-and-celebrate tone of some earlier years, there is at least a measure of joy for environmentalists. "Twenty years ago," Dunk recalled, "recycled papers were a resounding failure, but now the majors (IBM, W.R. Grace, et al.) - as well as the environmental waste companies such as Browning-Ferris - are looking recycled as well as restructured."

But even in the new mood of corporate modesty and introspection, Dunk cannot resist suggesting one further reduction: "If we can cut these reports in half, of course, we will save our eyes as well as some forests."