The category-partition method is a systematic approach for creating functional test suites. It involves analyzing the system specification, writing formal test specifications, and using a generator tool to produce test descriptions from which test scripts are written. The method allows testers to easily modify test specifications and control the complexity and number of tests by adding constraints. The goal of functional testing is to find discrepancies between the actual behavior of the system and its desired behavior as described in the specification. Functional tests can be derived from specifications, design information, or code. The category-partition method uses partitioning to generate tests, starting with the functional specification and decomposing it into testable units. The method includes formal test specifications and a generator tool that produces test cases. The process involves identifying functional units, partitioning categories into choices, determining constraints, and generating test frames. The method emphasizes both specification coverage and error detection. The test specification language (TSL) is used to implement the category-partition strategy, allowing testers to specify categories, choices, and constraints. The TSL has been used successfully in testing a version and configuration management (VCM) component, resulting in the discovery of numerous bugs. The method provides a systematic way to decompose functional specifications into test specifications, allowing testers to control the size and complexity of the test suite. The category-partition method is a promising foundation for further automation of specification-based functional testing.The category-partition method is a systematic approach for creating functional test suites. It involves analyzing the system specification, writing formal test specifications, and using a generator tool to produce test descriptions from which test scripts are written. The method allows testers to easily modify test specifications and control the complexity and number of tests by adding constraints. The goal of functional testing is to find discrepancies between the actual behavior of the system and its desired behavior as described in the specification. Functional tests can be derived from specifications, design information, or code. The category-partition method uses partitioning to generate tests, starting with the functional specification and decomposing it into testable units. The method includes formal test specifications and a generator tool that produces test cases. The process involves identifying functional units, partitioning categories into choices, determining constraints, and generating test frames. The method emphasizes both specification coverage and error detection. The test specification language (TSL) is used to implement the category-partition strategy, allowing testers to specify categories, choices, and constraints. The TSL has been used successfully in testing a version and configuration management (VCM) component, resulting in the discovery of numerous bugs. The method provides a systematic way to decompose functional specifications into test specifications, allowing testers to control the size and complexity of the test suite. The category-partition method is a promising foundation for further automation of specification-based functional testing.