Mind you, it was just a misunderstanding, a minor breakdown in communications.

The D.C. government, we have been assured by officials, wasn't trying to pull a fast one when it quietly drafted and published potentially far-reaching changes in the city's property-tax exemption rules for nonprofit organizations and left only 10 days for public comment.

The rules, published Jan. 11 in the little-read D.C. Register, probably would have gone into effect Feb. 1 if they hadn't been spotted by a few sharp-eyed lawyers representing nonprofit groups, who raised a fuss.

Melvin W. Jones, director of the D.C. Department of Finance and Revenue, insists that the proposed regulations would merely clarify, not change, current practices for granting property tax exemptions.

"The whole purpose of these rules was not to take away tax-exempt status from any of these groups," he said.

But many groups who have examined the proposal argue that the rules would open the door to the wholesale elimination of exemptions for hospitals, private schools and universities, group homes, nonprofit housing cooperatives, private libraries and some church properties.

Moreover, some of these groups are miffed that the department of finance didn't consult them before drafting the proposed rules, and left so little time for them to comment -- assuming they even saw the rules in the D.C. Register.

"The 10-day notice period given . . . is punitive, and a blatant attempt to suppress comments on an extremely important matter affecting the welfare of literally hundreds of low-income residents of the District of Columbia," said Michael S. Levy, an attorney who represents a nonprofit, low-income housing cooperative.

The comment period is usually 30 days.

Faced with an uproar over the proposed rules, including a complaint from the Archdiocese of Washington, Jones has agreed to extend the period for public comment by a month.

About 9,000 separate groups and agencies enjoy tax-exempt status. The city estimates that it loses about $88 million a year in tax revenue just on property owned by nongovernment organizations that qualify for tax exemptions.

Matthew Watson, a lawyer for the Washington Council of Agencies, is willing to give the city the benefit of the doubt. He concedes the city didn't set out to eliminate tax exemptions. But he said that the District blundered by drafting language before first conferring with nonprofit groups and others with practical knowledge in this area.

Host Mayor Marion Barry became the center of a partisan squabble during last week's midwinter meeting here of the U.S. Conference of Mayors, stemming from his controversial release of a conference report on urban policy just a few days before the November election.

Back then, three Republican mayors complained that Barry, a Democrat, had breached conference etiquette by playing partisan politics in the release of a report highly critical of Reagan administration policies.

The issue resurfaced last week during the conference meeting at L'Enfant Plaza Hotel. New Orleans Mayor Ernest Dutch Morial, newly installed president of the conference, announced that the report would not receive official status until it had been reviewed by all members and underwent other standard review procedures.

Barry was chairman of a Special Committee on a National Urban Policy that drafted the report. Last week, he issued a five-page statement giving the history of the report and responding to criticism of his handling of its release.

Republican Mayor James E. Roark of Charleston, W. Va., said at the end of the meeting: "It was blatant, petty politics and that is what has many of us members of the minority Republican party in this organization concerned."

As for Barry's explanation, Roark said: "I think there's only one conclusion, and that is that Mayor Barry is a liar."

Barry had no immediate response, but Democrat Morial rushed to his defense. He described the executive board's action with regard to the report as "a remedial measure to correct perhaps some errors that might have occurred."

Morial rebuked Roark for attacking Barry and called for an end to the bickering over the report.