High Swirl Combustion Hardware Systems Command Health and Safety Commission High Speed Channel Homeland Security Council Human Systems Center Hardware/Software Coordination Health and Safety Code Health Services Command Hierarchical Storage Controller Headquarters and Supply Company High Speed Connector High-Speed Craft Hardware System Command Health Sciences Center Health Service Commissioner hematopoietic stem cells hepatic stellate cells Herschel Science Centre High Speed Connect Higher School Certificate Hospital for Sick Children Host System Component hysteroscopy haematopoietic stem cell haematopoietic stem cells haemopoietic stem cell haemopoietic stem cells Hall Social Coordinator Hampden-Sydney College