Categorical Semantics, Or Extending Data Types to Include Memory.- Algebraic (?) Specification of Conceptual Database Schemata.- OBSCURE, A New Specification Language.- Some Thoughts on Algebraic Specification.- Implementation Specifications.- The ASSPEGIQUE Specification Environment — Motivations and Design.- Towards Abstract User Interfaces for Formal System Specifications.- A Final Algebra Semantics for Errors and Exceptions.- OSI Transport Service Considered as an Abstract Data Type.- Observational Specification: A Birkhoff-Theorem.- Fair Conditional Term Rewriting Systems: Unification, Termination and Confluence.- Transformation of Interface Specifications.- Axiomatising Specification Theory.- On the Algebraic Specification of Domains.- Passing Compatibility is Almost Persistency.- Automatic Prototyping of Algebraic Specifications Using Prolog.- Error Handling for Parameterized Data Types.- Model Theory of Denotational Semantics.