The Project Explorer was designed to provide quick access to many settings of the Poject, Session, and individual Map Window components within the program. As stated earlier, a Project can have many simultaneous descendant sessions open with their own descendant Map Windows. The Project Explorer has a hierarchical relationship that allows Sessions to inherit properties from the Project and Map Window to inherit properties from the Session, which can be very convenient for setting the same properties across multiple Sessions and Map Windows.
The Project Explorer shows the relation between each of the individual components in the program as a set of descendant properties and objects. Typically, it is useful to have the Properties Window open in conjunction with the Project Explorer.
The top level node shows the name of the Project File being used. Following the Project node, there are 'Project Defaults'. These are items such as definitions of annotation files, shapefiles, basin average files, and TIN dataset definitions. When a new Session is created it inherits settings from the Project Defaults.
Once a Session (for example 'American River' shown below) is created, a set of 'Session Defaults' settings are created. Notice that some of the node descriptions in the figure below are in normal text, some are in bold text and some are grayed out. The nodes containing inherited items, such as the "Project Defaults" Internet Maps and shapefile (usa.shp), are listed in bold. Alternatively, the maps under the Map Window nodes are listed in normal font, as they are inherited from the Project or Session (i.e. in Session: "American River", Map Window: "Forecast Precipitation", the AmericanRiver.shp node is not inherited and not bolded).
Further note that the "AmericanRiver.shp" and "RussianSubbasins.shp" nodes have green filled in polygons with the average symbol, indicating that these are basin average maps. On the other hand, the "usa.shp" polygon has no filling, indicating this is a background map. Additionally, under the "Russian River" Session, the "Forecast Precipitation" Map Windows is open, as indicated by the bold text, but the "Observed Precipitation" Map Window is closed, as indicated by the grayed out text.