The author reports on a promise to name a chief academic officer as second in charge of the New York City schools which paved the way for Cathleen P. Black to succeed Joel I. Klein as the district's next chancellor. The compromise plan, announced amid intensifying debate over her selection by Mayor Michael R. Bloomberg, won a state waiver necessary for Ms. Black as a noneducator. Whatever the lingering questions about the appointment, the plan to pair Ms. Black with an experienced district educator cast a fresh spotlight on the position of chief academic officer, or CAO, which has become common in larger districts. Such a management setup has many supporters, but requires a strong sense of teamwork and a shared belief system to work well, education observers say. Ms. Black, who will take office after Mr. Klein steps down at the end of this month, was maintaining a low profile as of last week. She has made visits to the district's central offices and to schools, but those visits have been closed to the public to encourage frank discussion, district officials say.