Design Nomenclature / Systems & Spec

Line conventions

Also called alphabet of lines, line types, hidden line, centerline, dimension line, leader, extension line

This entry has not been translated yet and is shown in English.

The graded weights and dash patterns that carry meaning on a drawing: thick continuous for visible edges, dashed for hidden ones, chain-dot for centrelines and axes, thin continuous for dimension and extension lines, and a leader arrowing a note to the feature it describes. Weight is information, not styling.

One dimensioned part annotated with each line type in turn: thick visible outline, dashed hidden bore, chain-dot centreline through the hole, thin dimension lines with arrowheads between extension lines, and a leader running from a note to the chamfer it describes.

In practice

Flattened to a single weight by CAD defaults and by anyone exporting to SVG. A drawing with uniform strokes still prints — it just stops distinguishing an edge from an axis.

Not to be confused with

DatumA theoretically exact reference — plane, axis, or point — derived from a real feature and used to orient and locate everything measured from it. Datums are ordered primary, secondary, tertiary, and that order is the inspection setup: change it and identical tolerances measure differently.

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Related Confused with

In practice

Not to be confused with

Related

How this term connects

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