# Signals Intelligence Signals intelligence (SIGINT) is intelligence derived from signals and associated systems. Operational taxonomies commonly distinguish [[Communications Intelligence|COMINT]], [[Electronic Intelligence|ELINT]], and foreign instrumentation signals intelligence, while real systems and missions can cross those boundaries. ## Notebook evidence [[Scanned_20260730-1830]], PDF pages 2–4, maps SIGINT through [[ECHELON]], [[Five Eyes]], PRISM, Room 641A, STELLARWIND, and the Special Collection Service. [[Scanned_20260730-1913]], PDF page 30, separately compares the Five Eyes member states. ## Analytical rule Alliance membership, collection capability, legal authority, technical access, a particular event, and attribution are separate propositions. A name in the SIGINT map establishes research proximity, not operational participation. ## Source - [[Scanned_20260730-1830]], PDF pages 2–4. - [[Scanned_20260730-1913]], PDF page 30.