Namespace package
A feature of setuptools which makes it possible to distribute multiple, separate packages sharing a single top-level namespace. For example, the packages plone.theme and plone.portlets both share the top-level "plone" namespace, but they are distributed as separate eggs. When installed, each egg's source code has its own directory (or possibly a compressed archive of that directory). Namespace packages eliminate the need to distribute one giant plone package, with a top-level plone directory containing all possible children, e.g. plone/theme and plone/portlets.