TS 5620 EN ISO 6433

TS 5620 EN ISO 6433 is a standard concerned with the general rules for item numbers and related references on technical drawings. In practice, these references help identify the parts in an assembly clearly and link the drawing view to the parts list or other product documentation.

How item references function on a drawing

Item numbers are commonly used on assembly drawings to distinguish components one by one and to make it clear that design, production, inspection, delivery and maintenance teams are referring to the same part. As general technical context, a reference number is usually read together with the bill of materials, sectional views, detail callouts or exploded views, so the drawing communicates product structure in a more systematic way.

The subject of this standard is the application of item numbers in technical drawings. It provides a shared framework for how such references are handled in terms of placement, legibility and consistency; it does not define a product-specific design method or a manufacturing process.

Typical context and boundary of use

• Provides common conventions for reference markings used with mechanical assembly drawings and parts lists.
• Helps keep numbering practices aligned with the product structure shown on the drawing.
• Deals with graphical documentation practice rather than a specific fabrication technology.
• This record belongs to a withdrawn standard, so its main value is historical and documental in drawing practice.