A knowledge-based document layout system now in use in the production of the British Telecom Yellow Pages


Formation is a knowledge-based document layout system, originally designed for large classified directories and catalogues. It consists of a graphical user interface to a batch layout engine. The heart of this engine is an interpreter for the Layout Style Specification Language (LSSL), in which document layout styles are programmed. The Formation GUI offers dialog-based modification and reconfiguration of programmed styles, along with graphical display and control facilities for laying out individual documents.

Formation GUI

Business Perspective

Pindar Set Ltd., the UK company that originates the British Telecom Yellow Pages, has developed an international business strategy to market generic, customisable, knowledge-based layout software and services to publishers of classified directories and catalogues. Pindar's clients, such as BTYP, increasingly demand faster and more flexible responses to requests for change in the layout of their pages, in order to improve their correctness, useability, and aesthetics. Pindar also wishes to attract new clients from around the world to its directory and catalogue services. Formation is allowing Pindar to implement this strategy, providing the company with a system offering much greater flexibility and higher throughput than the many other batch layout systems in regular use around the world.

In addition to the software itself, Pindar required a full understanding of the system so that they could maintain it themselves in future, and develop it further independently of external support. As a technology transfer organisation, AIAI was able to provide visiting worker facilities through which Pindar staff could work with, and learn from, experienced members of the Formation project team.

Technical Perspective

Formation is a knowledge-based layout system, in the sense that it operates using the same kind of expert knowledge of principles and procedures that are employed by a human layout artist doing the same task. In contrast to other automatic layout systems, it does not do a constraint-based search for some nominal 'best' solution out of many possibilities. Rather, it uses the principle 'follow correct and explicit procedures and rules and you'll get the one and only acceptable result'.

Layout styles are expressed in LSSL, an object-oriented, domain-specific language with primitives such as get-space, align, paste and unpaste. Each style defines:

The strategy and methods can be parameterized to make them flexible and reusable in different styles, and the Formation GUI allows the non-programming operator to combine and configure methods quickly and easily between layout runs.

Formation can lay out a typical classified telephone directory at speeds in excess of 1500 pages per hour on a typical Pentium PC.

AIAI Last updated 29th May 1997
by Andrew Casson-du Mont