Alphabet of lines

It refers to a standardized set of line types used to convey different types of information on technical drawings and diagrams.

• Line conventions
• Drawing rules
• Alphabet of lines

• Technical marks

Line that usually indicates the center of holes, circles, and arcs. The line is thin and dark.

• Center line
• Middle line
• Central line
• Median line

A thick, dark (unbroken) line is used to show the outline of an object, visible edges, and surfaces.

• Outline line
• Silhouette line
• Border line
• Visible line

A long line followed by two short dashes is used to show the alternate position of a moving part.

• Visible Line

• Phantom Line

• Section Line

• Break line

A medium line with an arrowhead to show notes, labels for size, or special information about a feature.

• Leader Line

• Size Line
• Indicator Line
• Dimension Line

A thin and dark line is used to show the starting and ending of a dimension.

• extension line

• reference line
• centerline
• dimension line

A thin and dark line is used to show the size (span) of an object with a numeric value. It usually terminates with arrowheads or tick markings.

• A length line
• A width line
• A dimension line
• A height line

An extra-thick line is used to show cutaway views or a plane of projection where a section view is taken. The arrow indicates the direction of view.

• Cutting plane line
• View line
• Projection line
• Section line

The thin crosshatching line is used in sectional views to indicate different parts of an object or materials from which an object is manufactured.

• dimension line

• section line

• break line

• hidden line

Short dash lines are used to show nonvisible surfaces. Usually shows as medium thickness.

• Solid lines
• Long dash lines
• Hidden lines

• Short dash lines