From November, 1973, through June, 1976, depending on whom you ask, Mary Loughlin was either (a) a historian, or (b) an assistant branch head at the Naval Historical Center, a part-Navy, part-civilian outfit headquartered in old warehouse and munitions factory space on the grounds of the Washington Navy Yard.

Loughlin, her former coworkers and the center's telephone directory all testify that she was the assistant branch head of the historical research branch. He complaint - a formal complaint, spelled out on a U.S. Civil Service Commission form 894 ("Complaint of Discrimination in the Federal Government") - is that she preceded as well as succeeded by male assistant branch heads hired at the GS-11 level, while she served exclusively as a GS-9.

When she took the job, says Loughlin, "I was told that a tight budget prevented the job from becoming a GS-11 . . . I told myself, 'I'll give them a year.'"

A year later, when Loughlin put the question to her boss, Dr. William Morgan, she says Morgan told her that the average grade at the center had to be lowered. Loughlin continued to press her campaign for a raise, she says, and was turned down again and again, usually on the grounds that the center could not afford it. But other employees - three males and one female - did receive promotions during this period according to Loughlin.

On July 2, 1976 - fed up, she explains, with her inability to be elevated to the same grade level as her predecessor - she handed in her resignation. She had intended to let the matter rest there, she says, until three months later, when "they advertised my job as a GS-11 and I got mad all over again." Loughlin then applied for the job - her job, as she saw it - and when a male candidate was finally hired in August, 1977, Loughlin hired a lawyer and filed her complaint.

The Civil Service Commission, which handles discrimination complaints from federal employees (the Equal Employment Opportunity Commission serves the same function for private industry), reports it is receiving them at a rate of more than 5,000 a year, with the Navy coming in second (677 complaints in fiscal 1976) to the Postal Service (2,048).

Although the Naval Historical Center has yet to submit a formal response in Loughlin's case, Morgan her boss takes the position that she was never really an assistant branch head, despite being listed as such in the center's phone directory and despite duties that at least periodically included assigning work and approving overtime.

"In my absence she would sometimes act for me," says Morgan. But Loughlin's successor, he adds, has "broader responsibilities . . . is a Ph.D. and ultimately could be my relief." In any event, says Morgan, "Mary knew what the job level was when we appointed her."

Rear Adm. John D.H. Kane Jr. (retired), director naval history, says neither he nor the center can comment on Loughlin's case until it is resolved. But Mark Andrews, Loughlin's attorney and a discrimination specialist, anticipates that the center will point to factors other than sex in justifying its refusal to promote her.

Discrimination cases are become steadily more intricate and more subtle, says Andrews, compared to a few years ago when there was a "virtual state of apartheid," by sex as well as race, in many government offices.

Civil Services Commission rules apprently bar strict imposition of an education requirement for jobs in the "Historian-170" series. Although schooling can be substituted for experience when it comes time to decide if an applicant qualifies for a particular rate of pay. With three years on the job, for example, a historian can be promoted to the GS-11 level, while a Ph.D. with no experience can be hired straight off as a GS-11.

What Loughlin can't understand, she says, is why her nearly nine years altogether as a naval historian (she began as a GS-5 in 1967), plus nearly three years as a GS-9 assistant branch head (her own view of her last position), failed to qualify her for GS-11 status.

Several of Loughlin's ex-colleagues, cheering anonymously from the sidelines as she begins her campaign for vindication, portray her as practically a saint of the civil service. Says one: "She was the type of person . . . well, you would say the filing system is a mess, but she would take a look and figure out how it could be fixed. . . She would stay late to finish something, and she wouldn't necessarily take comp time when it was due her. She would take work home. She would come in on weekends."

In one respect, Loughlin was not a model employee - not from a management perspective, at any rate. She raised several stinks, she says, over personnel practices at the center as applied to women and blacks. When she felt a vacancy announcement in the photo archives had been designed to favor a particular male candidate over a female competitor, for example, she shot off a memo to her superiors. She also campaigned for a pay raise for a black library assistant who, Loughlin says, had been at the center more than 20 years, and was still only a GS-4 in the late 1960s.

According to past and present employees, the Naval Historical Center has a low over-all pay structure. "You might say everyone was discriminated against," say William Heimdahl, now a military archivist with the National Archives, "but to be honest the women probably fared worse than the men."

Women employees agree that they have fared worse, but have trouble citing any dramatic cases. Instead, they talk about how they are more vulnerable to such assignments as answering phones, brewing coffee and arranging office parties, and, at the same time, tend to be excluded from staff meetings, formal Navy get-togethers, and, above all, high-level promotions. In general, says one women professional employee, "they have archaic view of women . . . that if you're under 35 you're just waiting around to get married."

But promotions, these employees concede, are heavily influenced as well by "a large amount of importance placed on degrees."

When Loughlin resigned, her plan, she says, was to go into business for herself as a potter, operating out of the basement of the Capitol Hill house she shares with her sister, two dogs, three cats, a rabbit, and a smiling portrait of Gerald Ford (who got her vote). A year later, Loughlin reports that the pottery pays its own way, but not hers.

A Coast Guard brat whose father commanded destroyer escort ships during World War II and later served as director of the Coast Guard's officer candidate school in New London, Conn., Loughlin recalls spending long hours as a child wandering along the waterfront "climbing over things and inspecting things," and at the age of 9 learning to sail a friend's sister's 28-foot Herreschoff, a "fantastic handling" vessel.

At the University of New Hampshire, she majored in government, later taking a graduate course in historical geography at Catholic University, before abandoning further educational ambitions. An interest in Arctic exploration led her, while assigned to the ship's histories branch of the Naval Historical center, to write that Cdr. Robert Peary "claimed" to have discovered the North Pole. Privately, Loughlin doubts that Peary ever got closer than several hundred miles from the pole. But her superiors expression of scholarly skepticism - it was deleted from the final version of the volume she was preparing.

Loughlin's case won't necessarily wind in court, although her attorney, Mark Andrews, feels that's a likely destination. First, the Navy has to appoint an investigator, who will in turn present findings to a Civil Service Commission hearing examiner. The Naval Historical Center will then have na orrortunity to accept or reject the hearing examiner's ruling. If the center decides that the hearing examiner's ruling. If the center decides that it has not, after all, discriminated against Loughlin, she can appeal to a Civil Service Commission appeals board.

This process, from initial complaint through final adjudication by the Civil Service Commission, takes an average of about a year to complete, according to the CSC.

In the meantime, says Andrews, a complainant can file suit in U.S. District Court, and may choose to do so sooner rather than later because the CSC machinery is so time-consuming and, from Andrews' point of view, so unfruitful.As a result, many cases are pursued simultaneously in court and through the CSC, a situation that seems to make a mockery of the whole purpose of administrative review - that is, to save the parties the time and expense of full-scale litigation.

If she wins her case, Loughlin says, she will return to her job at the Naval Historical Center, but it could be "really uncomfortable," she allows.