VDM-10 Language Manual

Chapter 1
Introduction
The Vienna Development Method (VDM) [Bjørner&78, Jones90, Fitzgerald&08a] was originally
developed at the IBM laboratories in Vienna in the 1970’s and as such it is one of the longest
established formal method. This document is a common language manual for the three dialects
for VDM-SL, VDM++ and VDM-RT in the VDM-10 commonly agreed language revision. These
dialects are supported by both VDMTools [Fitzgerald&08b] (in the appropriate version) as well as
in the Overture open source tool [Larsen&10] built on top of the Eclipse platform. Whenever a
construct is common to the three different dialects the term “VDM languages” will be used. Whenever
a construct is specific to a subset of the VDM languages the specific dialect term mentioned
above will be mentioned explictly.
1.1 The VDM Specification Language (VDM-SL)
This document describes the syntax and semantics of the VDM-SL language which is essentially
standard ISO/VDM-SL [ISOVDM96] with a modular extension 1 . Notice that all syntactically
correct VDM-SL specifications are also correct in VDM-SL. Even though we have tried to present
the language in a clear and understandable way the document is not a complete VDM-SL reference
manual. For a more thorough presentation of the language we refer to the existing literature 2 .
Wherever the VDM-SL notation differs from the VDM-SL standard notation the semantics will of
course be carefully explained.
1.2 The VDM++ Language
VDM++ is a formal specification language intended to specify object oriented systems with parallel
and real-time behaviour, typically in technical environments [Fitzgerald&05]. The language is
based on VDM-SL [ISOVDM96], and has been extended with class and object concepts, which are
1 A few other extensions are also included.
2 A more tutorial like presentation is given in [Fitzgerald&98] whereas proofs in VDM-SL are treated best in [Jones90]
and [Bicarregui&94].
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