The implementation of hierarchical packages modifies the
cl:find-package function, and provides certain auxiliary
functions, package-parent, package-children, and
relative-package-name-to-package, as described in this section.
The function defpackage itself requires no modification.
While the changes to cl:find-package are small and described
below, it is an important consideration for authors who would like
their programs to run on a variety of implementations that using
hierarchical packages will work in an implementation without the
modifications discussed in this document. We show why after
describing the changes to cl:find-package.
Absolute hierarchical package names require no changes in the underlying Common Lisp implementation.