Fig. 3

Content model or class association diagram of DIRT. A class association diagram in UML [50] is a static structure diagram to describe the relationship between the contents or classes of a software system including their class attributes. This figure shows the custom contents or classes, their attributes and relationship within DIRT. The rectangular boxes represent the content, the text on top portion of the box represents the name of the content and the text in lower portion of the box represents important content attributes. The line connecting the boxes denote the content association. The symbols at the end of these lines represent the association type and the text on these lines represents the attributes of the association