$ dot -Tismap input.dot
Image Map: Server-side
Produces HTML image map files. This is a predecessor (circa 1994)
of the IMAP format. Most servers now use the latter.
URLs can be attached to the root graph,
nodes and edges. Since edge
links are attached to edge labels, an edge must
have a label for its
URL to be used. For both nodes and edges, if the URL has the escape
\N embedded in its string, this will be replaced with the
node or edge name.