1 Introduction

The BETA language is described in [MMN 93] which is the main reference to BETA. The BETA book is a tutorial description of BETA. As of today there is no language definition manual, but one in preparation. Short introductions to BETA may be found in [Madsen 99], and [MIA 94-26]. In addition the following documents are available:

• A structured context-free grammar for BETA .
• A summary of BETA Terminology.
• A Quick Reference Card for BETA.

This document describes modifications of the BETA language that have been made since the publication of the BETA book. These include modifications, clarifications as well as extensions:

• A number of new basic patterns have been introduced.
• The operations on basic patterns such as integer, char, boolean and real, and references are further specified.
• Repetition constructors have been introduced.
• Text literals are further specified and extended and support for UniCode text has been included.
• For imperatives, the type of a general imperative must be a basic pattern or a reference, a simple if-imperative has been introduced, the labeled compound imperative has been eliminated. There are various restrictions with respect to leave/restart of patterns. Inserted objects are implemented as dynamic objects.
• Virtual superpatterns are not implemented, but a final pattern may be used as a superpattern.
• The use of this(p)[] for component objects is specified.
• Low level primitives for bit manipulation.
• Finally there are some changes regarding dynamic denotations, concurrency, exception handling, structure objects and the fragment system.

In the following, the above mentioned changes will be described in detail. The reader is assumed to be familiar with [MMN 93]