Nonprofit organizations fear a proposed amendment to Philadelphia's tax regulations will allow the city to tax an array of activities that they have always assumed were exempt.

The city revenue commissioner said yesterday that proposed changes to the business-privilege tax regulations were being "misconstrued" and were not designed to generate new revenue.

Still, nonprofit experts said the proposed changes were broad enough to permit the city to tax universities for dorm fees, performing-arts theaters for concession-stand sales, and small community groups for fund-raising dinners.

The amendments, in practice, would require nonprofit groups to undertake bookkeeping and administrative changes that could be more costly than the taxes.