Editing Engineering drawing (section)

==Relationship to model-based definition (MBD/DPD)==

For centuries, engineering drawing was the sole method of transferring information from design into manufacture. In recent decades another method has arisen, called [[model-based definition]] (MBD) or digital product definition (DPD). In MBD, the information captured by the CAD software app is fed automatically into a CAM app ([[computer-aided manufacturing]]), which (with or without postprocessing apps) creates code in other languages such as [[G-code]] to be executed by a CNC machine tool ([[numerical control|computer numerical control]]), [[3D printing|3D printer]], or (increasingly) a hybrid machine tool that uses both. Thus today it is often the case that the information travels from the mind of the designer into the manufactured component without having ever been codified by an engineering drawing. In MBD, the [[data set|dataset]], not a drawing, is the legal instrument. The term "technical data package" (TDP) is now used to refer to the ''complete package of information'' (in one medium or another) that communicates information from design to production (such as 3D-model datasets, engineering drawings, engineering change orders (ECOs), [[specification (technical standard)|spec]] revisions and addenda, and so on).

It still takes CAD/CAM programmers, CNC setup workers, and CNC operators to do manufacturing, as well as other people such as quality assurance staff (inspectors) and logistics staff (for materials handling, shipping-and-receiving, and [[front office]] functions). These workers often use drawings in the course of their work that have been produced from the MBD dataset. When proper procedures are being followed, a clear chain of precedence is always documented, such that when a person looks at a drawing, they are told by a note thereon that this drawing is not the governing instrument (because the MBD dataset is). In these cases, the drawing is still a useful document, although legally it is classified as "for reference only", meaning that if any controversies or discrepancies arise, it is the MBD dataset, not the drawing, that governs.