A PatternSystem is neither a PatternCatalog nor a
PatternLanguage.
Buschmann et al. say in their new book (p. xiii,
PatternOrientedSoftwareArchitecture by the PartyOfFive,
Wiley, 1996):

"We call this approach ''pattern-oriented system architecture.''
We talk about ''pattern systems'', in which patterns
are not just collected into a heterogeneous container,
but are also grouped according to appropriate criteria.
The GoF book started this categorization effort
by dividing patterns into 'creational','structural',
and 'behavioral' groupings.
We try to take the next step by grouping patterns according to finer-grained criteria such as interactive
and adaptable systems, organization of work, communication
and access control."
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For an introduction to Patterns:
* http://www.cmcrossroads.com/bradapp/docs/patterns-intro.html
For a jumping off place:
* DesignPatternsBook
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[ PatternLanguageTaxonomy ]