A package is a collection of types. A package is defined by a package diagram. Packages can be provided (that is defined) together with a system diagram (or together with another package diagram) or they can be used by means package identifiers.
A package may contain definitions of types, data generators, signal lists, remote specifications and synonyms. Definitions within a package are made visible to a system definition or other package definitions by a package-reference-clause (use clause). All (or selected) definitions of packages provided in this way will be visible in the system definition (or in the new package).