CENTER  LINES—Lines that indicate the center of a circle, arc, or any symmetrical object; consist of alternate long and short dashes evenly spaced. CIRCLE —A  plane  closed  figure  having  every  point  on its  circumference  (perimeter)  equidistant  from  its center. CIRCUMFERENCE—The length of a line that forms a  circle. CLEVIS—An open-throated fitting for the end of a rod or shaft, having the ends drilled for a bolt or a pin. It provides a hinging effect for flexibility in one plane. COLUMN—High-strength vertical structural members. COMPUTER-AIDED   DRAFTING   (CAD)—A method  by  which  engineering  drawings  may  be developed  on  a  computer. COMPUTER-AIDED     MANUFACTURING (CAM)—A method by which a computer uses a design to guide a machine that produces parts. COMPUTER  LOGIC—The electrical processes used by a computer to perform calculations and other functions. CONE—A solid figure that tapers uniformly from a circular base to a point. CONSTRUCTION   LINES—Lightly drawn lines used in  the  preliminary  layout  of  a  drawing. CORNICE—The projecting or overhanging structural section of a roof. CREST—The surface of the thread corresponding to the major diameter of an external thread and the minor diameter of an internal thread CUBE—Rectangular solid figure in which all six faces are  square. CUTTING PLANE LINE—A line showing where a theoretical cut has been made to produce a section view. CYLINDER —A solid figure with two equal circular bases. DEPTH—The distance from the root of a thread to the crest,  measured  perpendicularly  to  the  axis. DESIGNER'S WATERLINE—The  intended  position of  the  water  surface  against  the  hull. DEVELOPMENT —The process of making a pattern from the dimensions of a drawing. Used to fabricate sheet  metal  objects. DIGITAL—The  processing  of  data  by  numerical  or discrete  units. DIMENSION  LINE—A thin unbroken line (except in the  case  of  structural  drafting)  with  each  end terminating with an arrowhead; used to define the dimensions of an object. Dimensions are placed above the line, except in structural drawing where the line is broken and the dimension placed in the break DRAWING NUMBER—An   identifying   number assigned to a drawing or a series of drawings. DRAWINGS —The original graphic design from which a blueprint may be made; also called plans. ELECTROMECHANICAL  DRAWING—A  special type of drawing combining electrical symbols and mechanical  drawing  to  show  the  position  of equipment  that  combines  electrical  and  mechanical features. ELEMENTARY  WIRING  DIAGRAM—(1) A shipboard  wiring  diagram  showing  how  each individual  conductor  is  connected  within  the various connection boxes of an electrical circuit system.  (2)  A  schematic  diagram;  the  term elementary wiring diagram is sometimes used interchangeably  with  schematic  diagram,  especially a  simplified  schematic  diagram. ELEVATION—A four-view drawing of a structure showing front, sides, and rear. ENGINEER’S  SCALE—The scale used whenever dimensions are in feet and decimal parts of a foot, or when the scale ratio is a multiple of 10. EXPLODED  VIEW—A pictorial view of a device in a state of disassembly, showing the appearance and interrelationship  of  parts. EXTERNAL  THREAD—A thread on the outside of a member. Example: a thread of a bolt. FALSEWORK—Temporary  supports  of  timber  or steel  sometimes  required  in  the  erection  of  difficult or  important  structures. FILLET—A  concave  internal  corner  in  a  metal component,  usually  a  casting. FINISH MARKS—Marks used to indicate the degree of smoothness of finish to be achieved on surfaces to be machined AI-2