Intelligence Community Directive Number 206: Sourcing Requirements for Disseminated Analytic Products (Effective October 17, 2007) [open pdf - 3MB]
"This Intelligence Community (IC) Directive (ICD) establishes a Director of National Intelligence (DNI) requirement that disseminated analytic products must contain consistent and structured sourcing information for all significant and substantive reporting or other information upon which the product's analytic judgments, assessments, estimates, or confidence levels depend. Thorough and consistent documentation enhances the credibility and transparency of intelligence analysis and enables consumers to better understand the quantity and quality of information underlying the analysis."
ICD 206; Intelligence Community Directive No. 206
Office of the Director of National Intelligence: http://www.odni.gov/