Subchapter 9.6 – Block Airspace and Traffic Restrictions
IFR airspace is sometimes blocked for military operations, emergency procedures, or other special activities. When airspace is blocked, it is published in NOTAMs and appears on your moving map or flight planning software. A blocked altitude range or lateral area is not available for civilian IFR traffic.
Examples:
"Airspace blocked Flight Level 200 to Flight Level 250, Monday to Friday, 0800-1600 UTC for military training."
"Restricted Airspace R-250 blocked, supersonic operations in progress."
"Block Airspace B-24 closed to civilian traffic, emergency operations."