Editing Engineering drawing (section)

=== Line styles and types ===
[[File:Line types.svg|right|thumb|210px|Standard engineering drawing line types]]
A variety of line styles graphically represent physical objects. Types of ''lines'' include the following:
* ''visible'' – are continuous lines used to depict edges directly visible from a particular angle.
* ''hidden'' – are short-dashed lines that may be used to represent edges that are not directly visible.
* ''center'' – are alternately long- and short-dashed lines that may be used to represent the axes of circular features.
* ''cutting plane'' – are thin, medium-dashed lines, or thick alternately long- and double short-dashed that may be used to define sections for [[cross section (geometry)|section views]].
* ''section'' – are thin lines in a pattern (pattern determined by the material being "cut" or "sectioned") used to indicate surfaces in section views resulting from "cutting". Section lines are commonly referred to as "cross-hatching".
* ''phantom'' – (not shown) are alternately long- and double short-dashed thin lines used to represent a feature or component that is not part of the specified part or assembly.  E.g. billet ends that may be used for testing, or the machined product that is the focus of a tooling drawing.

Lines can also be classified by a letter classification in which each line is given a letter.
* '''Type A''' lines show the outline of the feature of an object. They are the thickest lines on a drawing and done with a pencil softer than HB.
* '''Type B''' lines are dimension lines and are used for dimensioning, projecting, extending, or leaders. A harder pencil should be used, such as a 2H pencil.
* '''Type C''' lines are used for breaks when the whole object is not shown. These are freehand drawn and only for short breaks. 2H pencil
* '''Type D''' lines are similar to Type C, except these are zigzagged and only for longer breaks. 2H pencil
* '''Type E''' lines indicate hidden outlines of internal features of an object. These are dotted lines. 2H pencil
* '''Type F''' lines are Type E lines, except these are used for drawings in electrotechnology. 2H pencil
* '''Type G''' lines are used for centre lines. These are dotted lines, but a long line of 10–20&nbsp;mm, then a 1&nbsp;mm gap, then a small line of 2&nbsp;mm. 2H pencil
* '''Type H''' lines are the same as type G, except that every second long line is thicker. These indicate the cutting plane of an object. 2H pencil 
* '''Type K''' lines indicate the alternate positions of an object and the line taken by that object. These are drawn with a long line of 10–20&nbsp;mm, then a small gap, then a small line of 2&nbsp;mm, then a gap, then another small line. 2H pencil.