Line Conventions

An Object Line is a thick, solid lines show the visible edges, corners, and surfaces of a part. Object lines stand out on the drawing and cleary define the outline and features of the object.

Construction Lines are a temporary linework entities that can be used as references when creating and positioning other subjects or linework.

Hidden Lines are consisted of short and long dashes to show that the interior detail of the object is not visible or seen to the person from the outside but on a design or sketch it is shown.

Center Lines are the design or drawing of the center of arcs, circles, or symmetrical parts. These are used to identify where the center location is for the mentioned above. 

Section Lines are special lines placed on a drawing which identifies the area of the drawing through which an imaginary cuthas been made to reveal internal details.

Short-Break Lines are lines that are thick, wavy solid lines that are drawn freehand. When this break lines is used to shorten an object, you show where the part your are going to remove to reveal or show the detail behind that part.

Long-Break Line are thin solid lines that have zigzags to indicate a break. Long-Break Line used to shorten the view of long uniform objects or sections, with detail.

Dimension Lines are fine, dark, solid line with arrowheads on each end. Dimension lines indicate the measurements of objects in a drawing.

Extension Lines are lines that extend from the surface of the object and establishes the size of the dimension. The extension line doesn't touch the object lines though and extend slightly past the dimension line. Extennsion lines are used to display a measurement.

Leader Lines are lines that show the dimensions of arcs, circles and details. The Leader line points at the arc or circle and shows the dimension of the arc or circle.