NEW YORK -- Perhaps because he was busy with other things -- like the news, for instance -- Brian Williams let last week's minor milestone of six months since replacing Tom Brokaw as NBC's chief anchor go unnoticed.
''Here is the God's honest truth," Williams said. ''Until your phone call, I had not realized the anniversary was upon me."
They have been six months of extraordinary change in the evening news after two decades of stability. Dan Rather stepped down, and the ''CBS Evening News" was revamped when Bob Schieffer took over. Peter Jennings announced he has lung cancer, and he hasn't been seen on ABC in two months.
With all this churn, what's remarkable is that there has been little obvious difference in viewing patterns. Given a chance to try something new, few people have bothered.
The pecking order is the same as it was during the final months of the Brokaw-Jennings-Rather triumvirate: NBC first, ABC a close second, and CBS an increasingly distant third.
''I am thrilled with where we are," Williams said, ''and, like any tough, cyclical business, it's about the long haul."
Williams's broadcast has maintained its lead despite signs that, like the morning and late-night shows, NBC's weakness in prime-time may be starting to hurt the network around the clock. ''Nightly News" viewership for the past six months is down 6 percent from the same period a year ago.
ABC's ''World News Tonight" is off 3 percent in the same measurement. But Jennings's absence has had no ratings impact and ABC has beaten NBC in the important 25-to-54-year-old demographic for two ratings ''sweeps" months in a row.
Despite Schieffer's folksy style and a format change to emphasize ''CBS Evening News" correspondents, that broadcast continues to lose ground. It was off 8 percent, according to
''This proves to me that for as much as the networks put the face of the anchors on the broadcast, the real reason why viewers watch it has been for the news," said Andrew Tyndall, a consultant who studies the content of network news broadcasts.
Or, perhaps, because they're watching something else before the network newscasts and simply don't bother changing the channel.
Jon Banner, executive producer of ''World News Tonight," cautioned that just because the rankings hadn't changed doesn't mean there isn't something going on. He pointed to ABC's demographic gains and noted that it took six years for Charles Gibson and Diane Sawyer of ''Good Morning America" to pull so close to NBC's ''Today" show.
''These things don't happen too quickly," Banner said. ''Anybody who has studied the industry knows that."
CBS is the only network to significantly change the way it delivers the news, and it's likely this is only the start, with executives considering a multiple-anchor format. ABC has emphasized how it is still doing Jennings's broadcast, only without Jennings. NBC's ''Nightly News" is structured the same way with Williams as it was with Brokaw.
''Remember," Williams said, ''part of my pledge was not to change what was working. The things that people say to me that they've noticed are all stuff around the margins. What it usually comes down to is a simple change in writing style."
He may lean heavily on news about veterans or US history because those are two areas he's interested in.
He writes most of his script for each night, beginning about 4:30 p.m. Williams writes from back to front, so the first thing he says on the air is usually the last thing he wrote.
''Anyone here can tell you that I would sooner have no Teleprompter and look right into the camera than to read something that I didn't write or hadn't seen before," he said. ''It scares me to death. I have a phobia about it. I think that's what makes your broadcast. I think people can tell if you wear the words more comfortably."
Williams shows the same tendency as Brokaw to try to take a step back, to put big events, such as a papal transition, in perspective. When Watergate's anonymous source Deep Throat was unmasked last week, Williams opened the broadcast by saying, ''The mystery of our age is no more."
It's a tightrope walk that can lead to either poignant moments or embarrassing overreaches.
Williams, who's traveled to Indonesia, Iraq, Italy, and Oklahoma in the past six months, is also getting used to a life with his passport always in his pocket and a suitcase always packed.
''You know waking up in the morning that you're not necessarily going to sleep in the same bed that night," he said.