Alphabet of Lines

• Alphabet of Lines

  • line symbols used in technical drawing
  • Used to express the features of design products clearly and accurately
• Object / Visible Lines


  Thick dark line used to show outline of object visible edges and surfaces
• Construction Line


  Very light and then line used to construct layout work.
• Extension Line


  Thin and dark line used to show the starting and ending of dimension.
• Dimension Line

  • Thin and dark lines used to show the size or span of an object with a numeric value.
  • With arrowheads or thick markings
• Hidden Line


  Short dash lines used to show surface edges or corners that are hidden from view.
• Center Line


  Thin and dark long and short dash lines, usually indicates center of holes circles and arcs.
• Cutting Plane Line


  Bisects the object and provide a view of its interior features, arrow indicates the direction of view
• Short Break Line

  • Freehand
  • Used to remove or "break out" part of drawing for clarity and to shorten objects which have the same shape throughout their length and maybe too long to place on the drawing
• Long Break Line

  • Thin line with zigzags
  • Used for solid details or for assemblies containing open space.
• Leader Line 


  Medium line with arrowhead to show notes or label for size or special information about feature.
• Section Line


  Medium lines drawn at 45 degrees used to show the interior view for solid areas of cutting plane line.
• Phantom Line


  Thin line used to indicate alternate position for moving parts (Long, short, short, long)