A computer implemented system analysis and design method for use in a complex business environment characterized by a set of tightly linked business processes captures in a framework a world view of a business decision and/or a business application software system. A world view is defined by business objectives, constraints, assumptions, data, and underlying model used in business decision and/or the application software system. The framework is used to specify and document each business decision and/or business application software system in the complex environment. A BDML (Business Decision Markup Language) is used to implement the framework for specifying the world view of a business decision and/or a business application software system. A BDML processor comprises a syntax processor that checks the syntax correctness and syntax consistency within an individual and between different documents written in BDML, a logic processor that checks logical consistency between different documents written in BDML, in terms of the business objectives, constraints, assumptions, data, and underlying model among the different documents, and a knowledge-based processor including a knowledge base of business decisions, common choices for their decision support models and commercially available decision support systems, the knowledge-based processor providing suggestions for a set of BDML documents to improve consistency using the knowledge base.