A sea room to be kept for safety around a vessel, rock, platform, etc.. 2: The place assigned to a vessel when anchored or lying alongside a pier, etc.
International Maritime Organization (IMO) Sub-Committee on Safety of Navigation & Rijeka College of Maritime Studies, IMO Standard Marine Communication Phrases (SMCP), London, UK 2000. http://www.segeln.co.at/media/pdf/smcp.pdf, (Mrn Commun Phrases - Brit) {563}