Hyperlinks incorporated into device-dependent output. At present, used in ps2, cmap, imap and svg formats. For all these formats, URLs can be attached to nodes, edges and clusters. URL attributes can also be attached to the root graph in ps2, cmap and imap formats. This serves as the base URL for relative URLs in the former, and as the default image map file in the latter.

For svg, cmapx and imap output, the active area for a node is its visible image. For example, an unfilled node with no drawn boundary will only be active on its label. For other output, the active area is its bounding box. The active area for a cluster is its bounding box. For edges, the active areas are small circles where the edge contacts its head and tail nodes. In addition, for svg, cmapx and imap, the active area includes a thin polygon approximating the edge. The circles may overlap the related node, and the edge URL dominates. If the edge has a label, this will also be active. Finally, if the edge has a head or tail label, this will also be active.

Note that, for edges, the attributes headURL, tailURL, labelURL and edgeURL allow control of various parts of an edge. Also note that, if active areas of two edges overlap, it is unspecified which area dominates.