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Welcome to PSL/PSA

Welcome to the home page for PSL/PSA, probably the world's most powerful requirements modelling toolkit.

PSL/PSA - problem statement language/problem statement analyzer, as a concept, is more than 40 years old. It has not been available for several years now, although some organizations still retain copies which are used for complex system modelling projects. That is about to change!

Work is now under-way to make psl/psa available once again. It is being brought up to date for a modern platform and will be available in various versions. The new versions of psl/psa will not be porting or updating previously existing code - they will be rebuilt from the ground up implementing the concepts originally behind the tools.

This website provides details of the various projects underway. The website also contains material about the history of psl/psa.

Please register to participate in the website. Some material will be available publicly, but some will only be available to registered users. There is an associated discussion forum.


PSL/PSA-light will be available very soon. It is being developed using a subset of the original PSL/PSA. So much of the original PSL/PSA was used rarely, and included for very specific sponsor needs. It has been designed to provide the objects and relations used in most projects. Sign up and express your interest so you can hear first.

Read more: PSL/PSA-lite


As soon as the first version of PSL/PSA-lite has been released, work will continue to make available once again, the full capability of PSL/PSA® as most people will have known it. There may be some variation and work is underway to investigate the reasoning behind the inclusion of some of the original relations.

Read more: PSL/PSA®


Would you like a model or comprehensive description of your business or organization? Many organizations would. The best way to do that is have your own 'language' to use for describing your business, or even just part of it. This can be critical for tracking many different components of the business, looking for gaps and inconsistencies.

Read more: metaPSL®

© Geoffrey Darnton 1992-2018