...in the case of continuous programming.

If a musical selection, such as a symphony or an act of an opera, was more than one hour in length, and if identifying the station would interrupt the integrity of the selection, we were allowed to go more than one hour without identifying. The stipulation was that we would identify immmediately before and immediately after the selection, with "WUVT-FM, Blacksburg, Virginia."

Today's Part 73 of the FCC Rules and Regulations does not contain the phrase "continuous programming", but the language of Section 73.1201 says announcements should be made "...hourly, as close to the hour as feasible, at a natural break in program offerings."

This, of course, includes mumbling your real call letters and city of license between two commercials in your :50-after break, I guess.