General Module Icons
Modules are the primary graphic element used in module charts. Modules are used to represent the structure of the system. There are two types of modules: internal (solid rectangle) and external (dashed rectangle). The functionality of a module is shown by an activity chart.
Create Internal Module - creates an internal module. Name Existing Module - names an existing module. Create Environment Module - creates an environmental module, which is a module outside the scope of the topmost module in a particular module chart.Because module charts are hierarchical, an environmental module is usually resolved to a box in a chart higher in the chart hierarchy. However, an environmental module can be resolved to a box that is an internal module at a higher level. In this case it remains simply an environmental module when referenced in the lower chart.