Two years ago, Toby J. McIntosh, a tall, red-bearded reporter for the Bureau of National Affairs, asked to see the appointment logs of antitrust chief William F. Baxter. That request has grown into a major lawsuit that is likely to determine not only whether Baxter can keep his daily activities secret, but whether any government official can.

The outcome will decide whether businessmen who travel to Washington to discuss industry regulations or pending litigation will have the fact of the meeting splashed across the front pages.

The BNA case, now at the federal court of appeals here in Washington, is the legal vehicle for the ruling, but the situation is hardly unique. More and more, reporters and public-interest lobbying groups are asking for access to meeting schedules. Over the last two years, there have been at least half a dozen such requests at the Justice Department itself, including tries by The Washington Post to get the appointment lists of Attorney General William French Smith.

Another pending case involves a bid by the Environmental Defense Fund to get such material from various officials in the Information and Regulatory Affairs branch of the Office of Management and Budget. And Common Cause has gone after the logs of Interior Secretary James G. Watt and Anne Gorsuch when she was head of the Environmental Protection Agency.

All of these requests are made under the Freedom of Information Act, so the key legal argument is over whether such appointment books are the kind of "agency records" covered by that statute. The government insists that they are not, that they are private records that McIntosh has no more right to than he would to Baxter's personal Christmas card list.

Part of that argument is based on the contention that there is no set way of keeping appointment schedules, that it is a purely personal decision what kind of reminders each official keeps. "The agencies don't want these appointment calendars," insists Barbara Ward, the Justice lawyer who argues such cases at trial. "They're not interested in what I write down in my little black book that I am to do at 9 o'clock or 10 o'clock." And she doubts the value of making the logs public because they often do not reflect cancellations or last-minute additions, and "half of them are in hieroglyphics anyway."

But in addition to those legal arguments, Justice has a policy reason for not wanting the appointment schedules released: they would give a careful reader an early indication of pending investigations. "You get a pretty good picture of a good deal of non-public stuff" from appointment calendars, one insider says. In fact, since the controversy began, Baxter has changed his policy so that now he circulates a typed schedule; previously his assistants got actual photocopies of his appointment book, complete with notations about the subject of the meeting.

But BNA, with the support of such allies as The Post and the Reporters Committee for Freedom of the Press, looks at the logs quite differently. They are prepared by a civil service secretary on a government-supplied appointment book, and they are used by the top rank of the antitrust division to know when Baxter will be free. And at least most of the logs are in the Justice Department building right now, sitting in Baxter's secretary's desk, the litigants point out. All that goes together to make them "agency records," BNA's lawyers argue. To call them merely private memoranda is a "crabbed interpretation" which "cannot be squared with established precedent under FOIA," Anthony L. Young and Jane Siegler wrote in the BNA brief.

But in fact that is just what District Court Judge Harold H. Greene called them last November, fighting a 1980 Supreme Court ruling that the Military Audit Project could not get transcripts of telephone conversations kept by Henry Kissinger when he was secretary of state. But in that case, Kissinger had already given the records--under seal--to the Library of Congress. A major point of the new litigation is just how different the Baxter situation is because the logs are still easily accessible in a government building.

A colleague of Greene, Judge Aubrey E. Robinson Jr., issued a preliminary ruling in the Environmental Defense Fund case, calling the OMB appointment calendars agency records. And Common Cause got the Watt schedules after Interior decided it did not want to push its refusal all the way to a trial.

Of course, it is consistent with the Reagan administration interpretation of FOIA and appointment logs that officials can make them public if they want to. That's what Gorsuch did. In the Carter administration, Attorney General Griffin B. Bell not only posted his appointment calendar in the Justice press room--thereby probably whetting reporters' appetites for such data--but has more recently advocated such openness as good public policy.

Business groups generally have not gotten involved in the Baxter case. But they usually argue on the side of openness in government, and they advise their members not to count on keeping any conferences with an official a secret.

"When a private citizen has a meeting with a public official, that's public business," says Albert Fry, assistant executive director of the Business Roundtable. "The fact of the meeting is a matter of public record."