One version opens with a five-to-seven-minute presentation of the news of the day by John Roberts, the network's chief White House correspondent, complete with "two-ways" between Mr. Roberts and several reporters. After a commercial break, the pace of the broadcast slows, and two or three "60 Minutes"-style segments are presented, albeit not at "60 Minutes" length, the last of them light and more humorous. After another break, Mr. Roberts, who is neither seen nor heard introducing those segments, returns to wrap up the broadcast with a good-night.The elements of that particular version - one of several, and more of an experiment than a polished pilot - were described earlier this week by three CBS News employees, including two who had been present during a taping late last month in a studio at CBS's broadcast center on West 57th Street in Manhattan. All said the process was far too sensitive for them to be identified by name. Some elements were reported on Tuesday by USA Today. In an interview, Andrew Heyward, president of CBS News, confirmed the taping. But he cautioned that on that day, producers and executives had recorded a variety of material that could be edited in various ways as a means of experimenting with multiple formats. He also said that the participation of Mr. Roberts - once widely believed within CBS to be the probable successor to Dan Rather - should not be interpreted as a sign that Mr. Roberts (or anyone else involved) will be part of the next "CBS Evening News" iteration.