When creating material applications, it is necessary to reference surfaces that materials should be applied to when the material application is in effect. To that end, application areas are used, as application areas represent a group of surfaces. Note that application areas may also be used without a material application. When displaying a symbol in CET, a symbol will first look to the product it represents for an applicable material application. If one is not found, the symbol will then search through all of the application areas that exist on the project the product belongs to. It will attempt to match the surface in question to a surface ID in one of the application ares. If a match is found, that application area will be used.

Application areas have the following attributes:

• Code – Every application area must have a unique code to distinguish it from other application areas. These codes are never presented to the user.
• Surface IDs – A list of surfaces that the application area represents.
• Material Reference – A reference to a material, made by means of the material’s code. The use of this reference depends on the context of the application area. When the application area is reference by a material application, the material application’s material reference will override this reference. However, if the application area is reference in a ‘global’ context (as described above), this material reference will determine which material is applied to a surface in question.