Flesh out packaging implications section.

pep-0420.txt

@@ -188,10 +188,30 @@ Nick Coglan presented a list of his objections to this proposal
 (These need to be addressed here.)
 
 
-Package Implications
+Packaging Implications
-====================
+======================
 
-(Placeholder)
+Multiple portions of a namespace package can be installed into the
+same location, or into separate locations. For this section, suppose
+there are two portions which define "foo.bar" and "foo.baz". "foo"
+itself is a namespace package.
+
+If these are installed in the same location, a single directory "foo"
+would be in a directory that is on ``sys.path``. Inside "foo" would be
+two directories, "bar" and "baz". If "foo.bar" is removed (perhaps by
+an automatic packager), care must be taken not to remove the "foo/baz"
+or "foo" directories. Note that in this case "foo" will be a namespace
+package (because it lacks an ``__init__.py``, even though all of its
+portions are in the same directory.
+
+If the portions are installed in different locations, two different
+"foo" directories would be in directories that are on
+``sys.path``. "foo/bar" would be in one of these sys.path entries, and
+"foo/baz" would be in the other. Upon removal of "foo.bar", the
+"foo/bar" and corresonding "foo" directories can be removed.
+
+Note that even if they are installed in the same directory, "foo.bar"
+and "foo.baz" would not have any files in common.
 
 References
 ==========