...PDB, and the fact that it was 11.5 pages in length:
Deadly Mistakes
U.S. Investigators Knew About Planned Terror Attacks, Let the Suspects Get Away. More Clues That CIA and FBI Could Have Prevented the Attack on America
by Oliver Schröm
Die Zeit
October 1, 2002<
http://www.cooperativeresearch.org/timeline/2002/diezeit100102.html>
Excerpt (about two-thirds of the way down the webpage):
"Crawford, Aug. 6, 2001. U.S. president George W. Bush is on vacation. He wants to spend the whole month at his ranch in Texas. Every morning, however, he still receives his Presidential Daily Brief, or PDB, wherein the CIA informs the president about the country's security situation.
On this morning, the report is straight from the CIA director. His PDB runs 11 and one-half printed pages, instead of the usual two to three, and carries the title, "Bin Laden Determined to Strike in U.S." Therein the CIA chief explains that al Qaeda has decided to carry out attacks within the United States, and that presumably members of the terrorist organization have been in the country for some time. It is unclear whether the CIA director informed the president about the statements of arrested al Qaeda members. According to their confessions, the terrorist organization for some time has been thinking about hijacking planes and using them as missiles.