FOOTINGS —Weight-bearing  concrete  construction elements poured in place in the earth to support a structure. FORGING—The process of shaping heated metal by hammering or other impact. FORMAT  —The  general  makeup  or  style  of  a  drawing. FRAME LINES—The  outline  of  transverse  plane sections of a hull. FRENCH CURVE—An  instrument  used  to  draw smooth irregular curves. FULL SECTION—A   sectional   view   that   passes entirely  through  the  object. HALF  SECTION —A combination of an orthographic projection and a section view to show two halves of a  symmetrical  object. HATCHING—The lines that are drawn on the internal surface of sectional views. Used to define the kind or type of material of which the sectioned surface consists. HELIX —The  curve  formed  on  any  cylinder  by  a straight line in a plane that is wrapped around the cylinder with a forward progression. HIDDEN LINES—Thick,    short,    dashed    lines indicating the hidden features of an object being drawn. INSCRIBED  FIGURE —A figure that is completely enclosed by another figure. INTERCONNECTION  DIAGRAM —A diagram showing the cabling between electronic units, as well as how the terminals are connected INTERNAL THREAD—A thread on the inside of a member. Example: the thread inside a nut. ISOMETRIC DRAWING—A    type    of    pictorial drawing.  See  ISOMETRIC  PROJECTION. ISOMETRIC PROJECTION—A set of three or more views of an object that appears rotated, giving the appearance of viewing the object from one corner. All lines are shown in their true length, but not all right angles are shown as such. ISOMETRIC WIRING DIAGRAM—A   diagram showing the outline of a ship, an aircraft, or other structure, and the location of equipment such as panels and connection boxes and cable runs. JOIST—A horizontal beam used to support a ceiling. KEY—A small wedge or rectangular piece of metal inserted in a slot or groove between a shaft and a hub  to  prevent  slippage. KEYSEAT—A slot or groove into which the key fits. KEYWAY—A  slot  or  groove  within  a  cylindrical  tube or pipe into which a key fitted into a key seat will slide. LEAD—The distance a screw thread advances one turn, measured parallel to the axis. On a single-thread screw the lead and the pitch are identical; on a double-thread screw the lead is twice the pitch; on a triple-thread screw the lead is three times the pitch. LEADER LINES—Two,  unbroken  lines  used  to connect   numbers,   references,   or   notes   to appropriate  surfaces  or  lines. LEGEND—A  description  of  any  special  or  unusual marks, symbols, or line connections used in the drawing. LINTEL—A load-bearing structural member supported at its ends. Usually located over a door or  window. LOGIC DIAGRAM—A type of schematic diagram using  special  symbols  to  show  components  that perform  a  logic  or  information  processing  function. MAJOR DIAMETER—The  largest  diameter  of  an internal  or  external  thread. MANIFOLD—A  fitting  that  has  several  inlets  or outlets to carry liquids or gases. MECHANICAL  DRAWING—See    DRAWINGS. Applies  to  scale  drawings  of  mechanical  objects. MIL-STD (military standards)—A formalized set of standards  for  supplies,  equipment,  and  design  work purchased  by  the  United  States  Armed  Forces. NOTES—Descriptive writing on a drawing to give verbal  instructions  or  additional  information. OBLIQUE DRAWING—A type of pictorial drawing in which one view is an orthographic projection and the views of the sides have receding lines at an angle. OBLIQUE   PROJECTION—A view produced when the projectors are at an angle to the plane the object illustrated. Vertical lines in the view may not have the  same  scale  as  horizontal  lines. OFFSET  SECTION—A section view of two or more planes in an object to show features that do not lie in the same plane. AI-3