- Squares are sub-programs or packages Double-line means Package. - Parallelograms relate to tasking (either task or protected type) - Dashed Lines refer to generics or abstractions - A Slash through a type means it is a sub or derived type. A Slash through an object means it is a constant. - Ovals refer to variables, or if a slash is through it to constants. Double Oval is used for source files.