It is possible to specify default values for all node or edge attributes in a top-level graph or subgraph. The default attributes are specified as follows:
These default specifications can appear anywhere in a top-level graph or subgraph specification and apply to all nodes and edges respectively (including back edges, near edges and bent near edges) where the corresponding attribute is not set explicitly. This default specification applies until another default specification for the same attribute appears or until the end of the subgraph or top-level graph specification is reached.