A schema can export multiple packages, with each package having a name that is unique within its exporting schema (across both exported and imported packages). A package name does not have to be globally unique.
For clarity of implementation and use, subschemas of exporting schemas cannot inherit packages exported from superschemas. Any functionality exported by a schema is already available to subschemas via schema inheritance.
For an exported package to be used in another schema, that schema must import it.
For an overview of restrictions when exporting or importing packages, see "Summary of Restrictions when Using Packages", later in this chapter.