The Reagan administration, under a 1982 executive order that spelled out new rules for defining government secrets, has been classifying more documents and declassifying far fewer.

According to the annual report of the Information Security Oversight Office, the total number of "classification decisions" in fiscal 1984 was 19,607,736, an increase of 9 percent over the year before.

Fiscal 1983, the first full year under the Reagan order, produced 18,005,151 classification decisions, an increase of about 3 percent over 1982 when rules from President Jimmy Carter's administration were still in effect.

The systematic declassification of old records -- an effort begun in 1972 by President Richard M. Nixon -- also has flagged under the Reagan order, but proceeded faster in 1984 than in 1983.

In 1983, 12.4 million pages of old government secrets were scrutinized, according to ISOO director Steven Garfinkel, and 7.8 million, or 63 percent, were declassified. In 1984, 12.8 million pages were reviewed and 10.9 million, or 86 percent, were declassified.

By contrast, in 1982, 19.5 million pages were reviewed and 16.6 million pages, or 85 percent, were declassified. In 1981, 31.3 million pages were reviewed and 28.5 million, or 91 percent, were declassified.

In short, there were more than twice as many records checked in the final two years of the Carter order, and more than twice as many pages declassified.

Garfinkel attributed the drop-off in declassified documents to two factors: dwindling appropriations, especially for the National Archives and Records Administration, and the declining number of records left from World War II that remain to be reviewed under "bulk declassification methods."

"The easiest records to declassify are the ones that pertain to military operations," Garfinkel said. "Now most of the records from the World War II era have been declassified. Now you're talking about records that are more recent and that do not pertain to military operations for the most part."

In addition, the Reagan order canceled a requirement that all agencies conduct a systematic review of classified records that are at least 20 years old.

Now only the Archives is required to make a systematic review and the threshold has been extended to 30 years.

Beyond that, Garfinkel said, the Archives is so strapped for money and space that "it has basically told the agencies, 'Don't send us the records, especially classified records, because we don't have room for them.' "

When the controversial Reagan order was promulgated, some critics said it would make documents easier to classify and harder to declassify. His changes:

* Eliminated a requirement that a document could be classified only if its release would cause "identifiable" damage to national security. The new rule permits documents to be classified if any unspecified sort of "damage" could be expected because of unauthorized disclosure. * Made it mandatory rather than voluntary to stamp government documents "top secret," "secret" or "confidential" whenever it was determined that those labels applied.

* Wiped out the so-called "balancing test" of the Carter order requiring that "the public's interest in access to government information" be considered when deciding whether to classify a document.

Critics such as Rep. Glenn English (D-Okla.), chairman of the House Government Operations subcommittee on government information, charged at the time that the clear message from the White House was "classify, classify, classify."

Garfinkel's report, submitted to the White House last week, took the position that the fears had proved unwarranted and that "the president's stated goal of achieving better protection for national security information while working to prevent unwarranted classification is clearly being met."

Garfinkel based his case primarily on the number of "original classification decisions" made each year. He said this is "the most important quantitative measurement of the information security system" because it represents "more precisely than any other reported statistic . . . the number of 'new secrets' created during the year."

According to Garfinkel, the first year under the Reagan order, fiscal 1983, showed "a dramatic 18 percent drop in the number of original classification decisions," from 1,055,152 in the final year of the Carter order to 864,099. Last year, fiscal 1984, showed a slight increase again, to 881,943, but Garfinkel said this was "only 2 percent higher than the prior year's unprecedented low figure."

The number of so-called "new secrets," however, has dropped primarily because of "the greater use of classification guides, especially in agencies that did not use guides until recently," such as the CIA and FBI.

Government secrets that are classified under a "guide," in turn, are counted as "derivative" actions rather than as "original" or "new secrets."

"Say the Air Force is contracting out with a defense contractor to work on part of a weapons system and it is a classified project," Garfinkel explained. "The Air Force will then produce something called a 'classification guide.' It describes elements of information likely to be produced as a result of working on the contract and, for each of these elements, it tells the contractor whether that element is to be classified, at what level and for how long."

Stamping such papers without a guide -- as was more frequently done in the Carter years -- amounts to an "original classification" decision, or "a new secret."

With the greater use of guides under the Reagan order, only the issuance of the guide itself is a "new secret." The stamping of secret papers in accordance with the guides is a "derivative action" that, according to ISOO, is no longer particularly important.

Garfinkel acknowledged that in terms of total numbers, "original" and "derivative" actions combined, more information is being classified.

He contended, however, that "where the numbers are going up the greatest, we're not talking about areas where there's any real question" of what should be classified.

"The numbers are going up in classified hardware, classified research and development and classified intelligence programs," Garfinkel said.

"That's where the numbers are going up," he said, "and they're going up because the expenditures the government is making in those areas is going up."