The graphviz package has been split into separate modular plugin
packages.  But the package descriptions do not explain what each
package is for. They all have the same generic text:

This package installs the libraries and headers necessary to link
graphviz library routines into an application. It also installs
additional man pages.

or just

This package contains the * plugin.


What does each plugin do?
How are we to know if a client package needs one or the other?

Separately, it might be helpful to provide a collective dependency
package (libgvplugin-all-dev and libgvplugin-all) to facilitate a full
graphviz installation. The graphviz binary package could Recommend (or
Suggest) it.