productivity of the package
<item>Conflicts, to specify a package which must NOT be installed
in order for the package to be configured
+ <item>Breaks, to specify a package which is broken by the
+ package and which should therefore not be configured while broken
</list>
Each of these dependencies can specify a version and a depedency on that
version, for example "<= 0.5-1", "== 2.7.2-1", etc. The comparators available