Despite ABC's upcoming fall show of the same name, the real Threat Matrix is a document the President reads each morning.

The crux of their briefings is the document formally titled "Terrorist Threats to U.S. Interests Worldwide," or more informally, the "Daily Threat Matrix."

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The document is "a list of every threat directed at the United States in the past 24 hours," Mueller said.

Government officials familiar with the Matrix, who spoke on condition of anonymity, described it as a daily compendium of a few pages to 30 or more. Each threat is entered in tabular format, with those considered the most severe listed first.