From Forum Nokia Wiki

Term Design may mean different things depending on the context. Industrial and hardware design, software architecture design, and UI design.

This Architecture/Design category is meant for articles touching software architecture design and topics especially of intrest for people like sofware architects and designers.

There is another caterory, Mobile Design, which is focusing on topics such as user interface, interaction and graphics design, topics especially of interest for creative professionals, typically referred simply as "Designers".

Industrial and hardware design is hardly touched in this developer's wiki, therefore there is no specific category for that purpose.