Based on incorrect information from the Postal Commission, yesterday's Business & Finance Section said that the commission found that a magazine published by four public television stations used material mailed by the Corporation of Public Broadcasting. The commission found that the mailing was done by Public Broadcasting Communications Inc., a company formed by the four stations.

The U.S. Postal Commission has ruled that four public television stations may not use existing second-class mail permits to send out copies of a new national monthly magazine -- a decision that could more than double mailing costs for The Dial in the short run.

The television stations, WETA in Washington, WTTW in Chicago, WNET in New York and KCET in Los Angeles, are expected to appeal the decision.

Harvey Altergott, general manager of the domestic mail classification division, ruled Wednesday that the stations could not use existing permits, such as they used to mail program guides that the Dial is replacing, to mail the new publication. Altergott found that The Dial appeared to be material of the Corporation for Public Broadcasting rather than of the stations.

The decision only covers the stations' interim ability to use a second-class permit. In a separate proceeding, they have applied for second-class permits specifically for The Dial. That request is pending.

Normally applications such as WETA's are handled routinely. In the case of a mailing permit for The Dial, however, allowing WETA to use its lower-cost mailing permit had been challenged by Phillip Merrill, publisher of The Washingtonian. The Dial, which carries advertising and local inserts about public television programing in a national magazine of general interest, competes with The Washingtonian for advertising revenue.