5. — METALS. Includes such items as structural steel,  open-web  steel  joists,  metal  stud  and  joist systems,   ornamental   metal   work,   grills,   and louvers. 6. —  WOOD AND PLASTICS. Includes wood and wood framing, rough and finish carpentry, foamed plastics, fiber-glass reinforced plastics, and laminated plastics. 7. —  THERMAL  AND  MOISTURE  PROTEC- TION.  Includes  such  items  as  waterproofing, dampproofing, insulation, roofing materials, sheet metal and flashing, caulking, and sealants. 8.    —  DOORS AND WINDOWS. Includes doors, windows,  finish  hardware,  glass  and  glazing,  storefront systems, and similar items. 9. —   FINISHES.   Includes   floor   and   wall coverings,  painting,  lathe,  plaster,  and  tile. 10.   — SPECIALTIES. Includes prefabricated products and devices, such as chalkboards, movable partitions,  fire-fighting  devices,  flagpoles,  signs,  and similar  items. 11.    —  EQUIPMENT. Includes such items as medical  equipment,  laboratory  equipment,  food  service equipment, kitchen and bath cabinetwork, and counter tops. 12. —  FURNISHINGS.  Includes  prefabricated cabinets, blinds, drapery, carpeting, furniture, and seating. 13. —  SPECIAL  CONSTRUCTION.  Includes prefabricated  structures,  integrated  ceiling  systems,  and swimming  pools. 14. —  CONVEYING  SYSTEMS.  Includes dumbwaiters,  elevators,  moving  stairs,  material- handling systems, and other similar conveying systems. 15. —  MECHANICAL.  Includes  plumbing, heating, air conditioning, fire-protection systems, and refrigeration systems. 16. — ELECTRICAL. Includes electrical service and distribution systems, electrical power equipment, electric  heating  and  cooling  systems,  lighting, telephone systems, and other electrical items. 17. —  EXPEDITIONARY  STRUCTURES. Include  tension  fabric  structures,  K-span  buildings,  and other similar items. Not all of the specification divisions are required for every construction project. Divisions that are not required  for  a  construction  project  are  normally omitted.  Sections  under  one  of  these  general  categories generally begin with GENERAL REQUIREMENTS for that category and continue with the SPECIFIC REQUIREMENTS.  An  example  of  a  section  of Division 15 (MECHANICAL) follows. In studying the guide specifications for plumbing which follow, study the drawing shown in figure 1-16, keeping in mind that these specifications are for this project and are listed as samples. DIVISION 15. MECHANICAL Section  15.  1a-  Plumbing 15.  1a-01.  GENERAL  REQUIREMENTS.  The work consists of a complete plumbing system, including the sanitary soil, waste, and vent piping; cold- and hot- water supply piping, water meter (if required), plumbing fixtures, hot-water heater, and other appurtenances. The system must be inspected, tested, and approved by local governing  plumbing  codes  before  burying,  concealing,  or covering the various piping systems. Each system must be complete and ready for operation except as specified or indicated   otherwise. 15.  1a-02.  SANITARY  SEWER,  BELOW- GROUND level, must be of extra-heavy cast-iron soil piping  and  fittings  of  the  bell-and-spigot  type, extending 3 to 5 feet beyond the foundation wall and graded not less than 1/8 inch per foot. The joint will be made from a good grade of twisted oakum uniformly and well-tamped into the joint and with a l-inch depth of hot poured lead, made in one pouring, and caulked tight.  All  horizontal  soil  connections  to  the  system must be accomplished by Y-fittings or combination Y and 1/8 bends. All changes in direction greater than a 1/8 bend must be of the long sweep pattern. Lines 1-13