What Is the Right Size for a Theme?

The Theme approach does not explicitly recommend any particular "size" for a theme. If a theme is measured by the number of design elements contained within, then the size will be dictated by what is necessary to support the particular requirement under design by that theme. Other design approaches provide some guidelines as to the size of their different models. For example, the OORam model provides some loose guidelines for the size of role models based on the notion that human short-term memory can manage seven plus or minus two notions at the same time. The suggested guideline, therefore, is that a role model should consist of between five and nine roles, where fewer than five roles should be synthesized into a larger role model, and where consideration should be given to further breaking up a model with greater than nine roles. The Theme approach, however, focuses on modularizing designs based on logical separations as ascertained from examination of the requirements specification, and not what the ultimate size of the theme might be.