In product development, it is often necessary to reference the constituent parts of an assembly. This can be done using a variety of methods, but the most common is to use ISO 6433. This International Standard provides rules for the presentation of part references in assembly representations, such as on assembly drawings or in related parts lists. By following these rules, it is possible to ensure that all parts are properly identified and that there is a consistent method of reference across all products. This can save time and frustration during the product development process, making it a valuable tool for any engineer or designer.