rpmgraph uses PACKAGE_FILE arguments to generate a package dependency graph. Each PACKAGE_FILE argument is read and added to an rpm transaction set. The elements of the transaction set are partially ordered using a topological sort. The partially ordered elements are then printed to standard output.
Nodes in the dependency graph are package names, and edges in the directed graph point to the parent of each node. The parent node is defined as the last predecessor of a package when partially ordered using the package dependencies as a relation. That means that the parent of a given package is the package's last prerequisite.
The output is in dot(1) directed graph format, and can be displayed or printed using the dotty graph editor from the graphviz package. There are no rpmgraph specific options, only common rpm options. See the rpmgraph usage message for what is currently implemented.