Modification such as adding windows, engines, undercarriage, even additional wings can be executed to any component drawing that forms part of the assembly.

N.B. Remember that modifications to design components should be made to the design and not to the assembly. By doing this modifications will be automatically shown in the assembly.

This type of design work using CAD assembly is known as "Electronic Product Definition". British Aerospace use this technique for the design of their new aircraft including the new A3XX which will challenge the Boeing 747. The design team no longer use conventional paper based drawings. This is a major development in design, beyond the traditional work-share arrangements of the Airbus Industries consortium, where individual partners took specific responsibility for certain aspects of the design.

With "Electronic Product Definition", design teams from around the world are able to work on integrated components, each drawing on the combined skills of all partners. This means that a component in the fuselage might be designed by a team from Germany whilst also being worked on by a design team from Britain. This shows the international co-operation that now has to go into the manufacture of such an expensive product. Design is now about working in a global market and in global teams.