There are many things Edith Boyle simply will not discuss.

She will not say how many of the country's military secrets are locked away inside her drab green file safes and her coifed blond head. "I know a lot," she said in her office at the Pentagon. "Anybody who has worked here as long as I have knows a lot. But I can't tell anybody anything."

She will not elaborate on the hundreds of messages she relayed from the Joint Chiefs of Staff to Gen. Douglas MacArthur during the Korean War. "Never," she said firmly.

And she will not reveal how old she was when she began working for the federal government 50 years ago, in the New Deal era of 1935. "Why, then, you'll know how old I am now," she said, blinking and looking taken aback, "and I don't tell my age."

Three wars have mobilized the nation, 17 secretaries of War and Defense have come and gone. But for half a century, Edith Boyle has held steady, serving her country with tightly sealed lips.

"On the outside, I just keep quiet," she said recently. "I'll know something, and I won't be sure if I read it in a newspaper or in a classified document, so I say nothing. Those people who leak secrets unintentionally? They just forget where they learned their information."

Defense Department officials say Boyle is one of only a handful of women who have reached the milestone of 50 years of service in the federal government -- and the only woman to do so at the Pentagon.

Last week, Defense Secretary Caspar W. Weinberger gave her a small gold and diamond pin, which she now wears daily, in a brief ceremony in his office.

Boyle, who knew Dwight Eisenhower when he was a mere lieutenant colonel, has no immediate plans to retire.

Although Boyle's current job title is administrative assistant in the Office of the Assistant Secretary for Manpower, Installations and Logistics, a sheaf of congratulatory letters from government officials lofty and lowly, past and present, credits her with "training" many of her superiors.

"I cannot remember a single occasion when I approached you for assistance that I came away empty-handed," wrote a retired U.S. Navy captain.

"The routine was remarkedly repetitious, starting with 'Edith, do you remember . . . ?' Inevitably, you did -- and then you would go on to describe from memory not only the event, but its history, its players and its outcome, and then more times than not, know exactly where in the files of antiquity to find the supporting documentation," the captain wrote.

Not only was Boyle always there with the answers, she was always there.

"She has 2,500 hours . . . of accumulated sick leave," said her husband of 30 years, Robert Boyle, who works for the D.C. deputy mayor for finance. "I've seen her drag herself to work. Sick, well, she always goes. She's just a throwback to all those good old things like patriotism and loyalty to the job."

Edith Boyle, a Nebraska farm girl from the tiny town of Allen, began her civil service in 1935 as a secretary for the Works Progress Administration in Lincoln, Neb. Four years later, she took a job in Washington, in the intelligence division of what was then called the War Department (before the creation of the Defense Department in 1947).

Boyle was one of the first workers to move into the Pentagon in the spring of 1942. The complex's 17 1/2 miles of corridors were still under construction, and Boyle and the other employes had to bring water from home and walk over muddy planks to get to their desks.

When Boyle worked for the Joint Chiefs of Staff, from 1945 to 1954, more than 90 percent of her work was classified, she said. During the Korean War, only she and one other woman had clearance to dispatch messages between the top military officials and MacArthur, who was commander in chief of the United Nations forces.

"Often we would work all night," she said. "We'd catnap on the sofas."

Boyle denies the legend that it was she who typed the message dismissing MacArthur from command in 1951. "I sent plenty of messages to MacArthur, some of them 20 pages long," she said, "but nobody typed that message. It was written by Gen. [Omar] Bradley himself."

By the time of the Vietnam War, Boyle was working in the logistics division, which meant that she assisted with the supplying and transporting of the military forces in Southeast Asia. "I knew where the troops were at the moment," she said, "and I knew where they were going to be the next week."

Robert Boyle recalls the time in the late 1960s when war protesters, lying across the steps of the Pentagon, tried to prevent his wife from entering the building. Troops with the 82nd Airborne Division, who were guarding the complex, bodily lifted Edith Boyle over the prone figures.

"Her philosophy was that they had the right to protest, and she had the right to work," he said.

Robert Boyle said there are times, at the end of a hectic week, when his wife mentions the possibility of retiring.

"Then comes Monday morning," he said, "and she's into that suit and charging off to the Pentagon again."