(After Konrad Zuse) A descendant of Ada, Modula-2, Mesa and Oberon-1, described by Christian Collberg <firstname.lastname@example.org> in his PhD thesis 1991.
Zuse supports several levels of information hiding. The Zuse type system includes fully hidden types (similar to Modula-2 opaque types but without any implementation restriction), semi-open pointer types (same as Modula-2 opaque types), extensible record types (similar to Oberon-1 public projection types but without the compiler hint), enumeration types, extensible enumeration types, and extensible subrange types.
A type can also be protected by specifying the operations that particular modules may perform (similar to C++ friend classes and Ada private types). Zuse also includes hidden and extensible constants and hidden inline procedures. In order to support the higher levels of information hiding the implementation employs partial intermediate code linking.
A version for Sun-3 is available.