ZEBRA fittings are marked with a red Z. These closures are secured during condition ZEBRA. You must have proper authorization to open fittings with this classification when the ship is in condition ZEBRA. You will find this classification on the following closures: All  remaining  doors  and  hatches  for routine access Access to all shops; labs; and commissary, utility, control, and hospital spaces Access to all offices Access  to  equipment  rooms  occupied when associated control room is in use Main access to machinery spaces Access to issue rooms Access to the steering gear room Access to the enclosed operating stations Access to hangar and flight deck control stations Access to the garbage disposal room Access to the trash burner and bin room CIRCLE ZEBRA fittings are marked with a red Z inside a red circle. These modified fittings are secured during condition ZEBRA. CIRCLE ZEBRA fittings may be opened with the com- manding officer’s permission during prolonged periods of general quarters. The opening of these fittings allows evolutions such as the preparation and  distribution  of  battle  rations,  opening  of limited sanitary facilities, ventilation of battle stations, and access for aviation personnel to the flight deck. When open, CIRCLE ZEBRA fittings must be guarded so that they may be closed immediately if necessary. You will find this classification on the following closures: • Limited doors or scuttles from the weather deck to the crews’ galley • Doors from aviators and flight crew ready rooms to the flight deck DOG ZEBRA fittings are marked with a red Z inside a black D. These modified fittings are secured during condition ZEBRA and darken-ship conditions. You must have proper authorization to open fittings with this classification when the ship is at either condition ZEBRA or darken ship. You will find this classification on the following closures: • Doors  to  the  weather  deck,  excluding those classified XRAY or YOKE, that do not have a darken-ship switch or a darken- ship curtain • Airports  (portholes) WILLIAM fittings are marked with a black W. These fittings are kept open during all material conditions. WILLIAM fittings are secured only as necessary to control damage or CBR con- tamination and to make repairs to the equipment served. You will find this classification on the following  fittings: Vital sea suction valves that supply the main and auxiliary condensers, fire pumps, and spaces that are manned during con- ditions XRAY, YOKE, and ZEBRA Vital valves that if secured would impair the mobility and fire protection of the ship CIRCLE WILLIAM fittings are marked with a black W inside a black circle. These fittings are normally kept open, as is the case with WILLIAM fittings.  They  must,   however, be secured to prevent the spread of damage and as a defense measure when a CBR attack is imminent. You will find this classification on the following closures: Doors to the pilot house, flag bridge, and signal shelter Ventilation systems to main and auxiliary machinery spaces, generator spaces, and other systems and fittings serving spaces in continuous use If access to a space is through a series of hatches and/or scuttles, all of the closures that provide that access must bear the same classifica- tion as that of the space. For example, a pump room is classified as CIRCLE YOKE. This means it is open during condition XRAY and closed during condition YOKE. All hatches, scuttles, and doors that provide access to the pump room must also be classified CIRCLE YOKE to allow routine access to the pump room. 7-18